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Version: 2.0.x

Writing Queries

Introduction

The QDSL allows the user to write plain Scala code, leveraging Scala's syntax and type system. Quotations are created using the quote method and can contain any excerpt of code that uses supported operations. To create quotations, first create a context instance. Please see the context section for more details on the different context available.

For this documentation, a special type of context that acts as a mirror is used:

import io.getquill._

val ctx = new SqlMirrorContext(MirrorSqlDialect, Literal)

The context instance provides all the types, methods, and encoders/decoders needed for quotations:

import ctx._

A quotation can be a simple value:

val pi = quote(3.14159)

And be used within another quotation:

final case class Circle(radius: Float)

val areas = quote {
query[Circle].map(c => pi * c.radius * c.radius)
}

Quotations can also contain high-order functions and inline values:

val area = quote {
(c: Circle) => {
val r2 = c.radius * c.radius
pi * r2
}
}
val areas = quote {
query[Circle].map(c => area(c))
}

Quill's normalization engine applies reduction steps before translating the quotation to the target language. The correspondent normalized quotation for both versions of the areas query is:

val areas = quote {
query[Circle].map(c => 3.14159 * c.radius * c.radius)
}

Scala doesn't have support for high-order functions with type parameters. It's possible to use a method type parameter for this purpose:

def existsAny[T] = quote {
(xs: Query[T]) => (p: T => Boolean) =>
xs.filter(p(_)).nonEmpty
}

val q = quote {
query[Circle].filter { c1 =>
existsAny(query[Circle])(c2 => c2.radius > c1.radius)
}
}

You can also use implicit classes to extend things in quotations.

implicit final class Ext(private val q: Query[Person]) extends AnyVal {
def olderThan(age: Int) = quote {
query[Person].filter(p => p.age > lift(age))
}
}

run(query[Person].olderThan(44))

(see implicit-extensions for additional information.)

Compile-time quotations

Quotations are both compile-time and runtime values. Quill uses a type refinement to store the quotation's AST as an annotation available at compile-time and the q.ast method exposes the AST as runtime value.

It is important to avoid giving explicit types to quotations when possible. For instance, this quotation can't be read at compile-time as the type refinement is lost:

// Avoid type widening (Quoted[Query[Circle]]), or else the quotation will be dynamic.
val q: Quoted[Query[Circle]] = quote {
query[Circle].filter(c => c.radius > 10)
}

ctx.run(q) // Dynamic query

Quill falls back to runtime normalization and query generation if the quotation's AST can't be read at compile-time. Please refer to dynamic queries for more information.

Inline queries

Quoting is implicit when writing a query in a run statement.

ctx.run(query[Circle].map(_.radius))
// SELECT r.radius FROM Circle r

Bindings

Quotations are designed to be self-contained, without references to runtime values outside their scope. There are two mechanisms to explicitly bind runtime values to a quotation execution.

Lifted values

A runtime value can be lifted to a quotation through the method lift:

def biggerThan(i: Float) = quote {
query[Circle].filter(r => r.radius > lift(i))
}
ctx.run(biggerThan(10)) // SELECT r.radius FROM Circle r WHERE r.radius > ?

Note that literal-constants do not need to be lifted, they can be used in queries directly. Literal constants are supported starting Scala 2.12.

final val minAge = 21  // This is the same as: final val minAge: 21 = 21
ctx.run(query[Person].filter(p => p.age > minAge)) // SELECT p.name, p.age FROM Person p WHERE p.name > 21

Lifted queries

A Iterable instance can be lifted as a Query. There are two main usages for lifted queries:

contains

def find(radiusList: List[Float]) = quote {
query[Circle].filter(r => liftQuery(radiusList).contains(r.radius))
}
ctx.run(find(List(1.1F, 1.2F)))
// SELECT r.radius FROM Circle r WHERE r.radius IN (?)

batch action

def insertValues(circles: List[Circle]) = quote {
liftQuery(circles).foreach(c => query[Circle].insertValue(c))
}
ctx.run(insertValues(List(Circle(1.1F), Circle(1.2F))))
// INSERT INTO Circle (radius) VALUES (?)

Schema

The database schema is represented by case classes. By default, quill uses the class and field names as the database identifiers:

final case class Circle(radius: Float)

val q = quote {
query[Circle].filter(c => c.radius > 1)
}

ctx.run(q) // SELECT c.radius FROM Circle c WHERE c.radius > 1

Schema customization

Alternatively, the identifiers can be customized:

val circles = quote {
querySchema[Circle]("circle_table", _.radius -> "radius_column")
}

val q = quote {
circles.filter(c => c.radius > 1)
}

ctx.run(q)
// SELECT c.radius_column FROM circle_table c WHERE c.radius_column > 1

If multiple tables require custom identifiers, it is good practice to define a schema object with all table queries to be reused across multiple queries:

final case class Circle(radius: Int)
final case class Rectangle(length: Int, width: Int)
object schema {
val circles = quote {
querySchema[Circle](
"circle_table",
_.radius -> "radius_column")
}
val rectangles = quote {
querySchema[Rectangle](
"rectangle_table",
_.length -> "length_column",
_.width -> "width_column")
}
}

Database-generated values

returningGenerated

Database generated values can be returned from an insert query by using .returningGenerated. These properties will also be excluded from the insertion since they are database generated.

final case class Product(id: Int, description: String, sku: Long)

val q = quote {
query[Product].insertValue(lift(Product(0, "My Product", 1011L))).returningGenerated(_.id)
}

val returnedIds = ctx.run(q) //: List[Int]
// INSERT INTO Product (description,sku) VALUES (?, ?) -- NOTE that 'id' is not being inserted.

Multiple properties can be returned in a Tuple or Case Class and all of them will be excluded from insertion.

NOTE: Using multiple properties is currently supported by Postgres, Oracle and SQL Server

// Assuming sku is generated by the database.
val q = quote {
query[Product].insertValue(lift(Product(0, "My Product", 1011L))).returningGenerated(r => (id, sku))
}

val returnedIds = ctx.run(q) //: List[(Int, Long)]
// INSERT INTO Product (description) VALUES (?) RETURNING id, sku -- NOTE that 'id' and 'sku' are not being inserted.

returning

In UPDATE and DELETE queries we frequently want to return the records that were modified/deleted. The returning method is used for that.

Note that most of these operations are only supported in Postgres and SQL Server

For example when we want to return information from records that are being updated:

val desc = "Update Product"
val sku = 2002L
val q = quote {
query[Product].filter(p => p.id == 42).update(_.description -> lift(desc), _.sku -> lift(sku)).returning(r => (r.id, r.description))
}
val updated = ctx.run(q) //: (Int, String)
// Postgres
// UPDATE Product AS p SET description = ?, sku = ? WHERE p.id = 42 RETURNING p.id, p.description
// SQL Server
// UPDATE Product SET description = ?, sku = ? OUTPUT id, description WHERE id = 42

When multiple records are updated using update.returning a warning will be issued and only the first result will be returned. Use returningMany to return all the updated records in this case.

You can do the same thing with updateValue.

// (use an UpdateMeta to exclude generated id columns)
implicit val productUpdateMeta = updateMeta[Product](_.id)
val q = quote {
query[Product].filter(p => p.id == 42).updateValue(lift(Product(42, "Updated Product", 2022L))).returning(r => (r.id, r.description))
}
val updated = ctx.run(q) //: (Int, String)
// Postgres
// UPDATE Product AS p SET description = ?, sku = ? WHERE p.id = 42 RETURNING p.id, p.description
// SQL Server
// UPDATE Product SET description = ?, sku = ? OUTPUT INSERTED.id, INSERTED.description WHERE id = 42

You can also return information that is being deleted in a DELETE query. Or even the entire deleted record!

val q = quote {
query[Product].filter(p => p.id == 42).delete.returning(r => r)
}

val deleted = ctx.run(q) //: Product
// Postgres
// DELETE FROM Product AS p WHERE p.id = 42 RETURNING p.id, p.description, p.sku
// SQL Server
// DELETE FROM Product OUTPUT DELETED.id, DELETED.description, DELETED.sku WHERE id = 42

When multiple records are deleted using delete.returning a warning will be issued and only the first result will be returned. Use returningMany to return all the deleted records in this case.

returningMany

Similar to insert/update.returning, the returningMany function can be used to return all the values that were updated/deleted from a query. Not just one.

Return all the records that were updated.

val desc = "Update Product"
val sku = 2002L
val q = quote {
query[Product].filter(p => p.id == 42).update(_.description -> lift(desc), _.sku -> lift(sku)).returning(r => (r.id, r.description))
}
val updated = ctx.run(q) //: List[(Int, String)]
// Postgres
// UPDATE Product AS p SET description = ?, sku = ? WHERE p.id = 42 RETURNING p.id, p.description
// SQL Server
// UPDATE Product SET description = ?, sku = ? OUTPUT id, description WHERE id = 42

Return all the records that were deleted.

val q = quote {
query[Product].filter(p => p.id == 42).delete.returning(r => r)
}

val deleted = ctx.run(q) //: List[Product]
// Postgres
// DELETE FROM Product AS p WHERE p.id = 42 RETURNING p.id, p.description, p.sku
// SQL Server
// DELETE FROM Product OUTPUT DELETED.id, DELETED.description, DELETED.sku WHERE id = 42

Postgres Customized returning

Returning values returned can be further customized in some databases.

In Postgres, the returning and returningGenerated methods also support arithmetic operations, SQL UDFs and even entire queries for INSERT, UPDATE, and DELETE actions. These are inserted directly into the SQL RETURNING clause.

For example, assuming this basic query:

val q = quote {
query[Product].filter(p => p.id == 42).update(_.description -> "My Product", _.sku -> 1011L)
}

Add 100 to the value of id:

ctx.run(q.returning(r => r.id + 100)) //: List[Int]
// UPDATE Product AS p SET description = 'My Product', sku = 1011L WHERE p.id = 42 RETURNING p.id + 100

Pass the value of id into a UDF:

val udf = quote { (i: Long) => sql"myUdf($i)".as[Int] }
ctx.run(q.returning(r => udf(r.id))) //: List[Int]
// UPDATE Product AS p SET description = 'My Product', sku = 1011L WHERE p.id = 42 RETURNING myUdf(p.id)

Use the return value of sku to issue a query:

final case class Supplier(id: Int, clientSku: Long)
ctx.run {
q.returning(r => query[Supplier].filter(s => s.sku == r.sku).map(_.id).max)
} //: List[Option[Long]]
// UPDATE Product AS p SET description = 'My Product', sku = 1011L WHERE p.id = 42 RETURNING (SELECT MAX(s.id) FROM Supplier s WHERE s.sku = clientSku)

As is typically the case with Quill, you can use all of these features together.

ctx.run {
q.returning(r =>
(r.id + 100, udf(r.id), query[Supplier].filter(s => s.sku == r.sku).map(_.id).max)
)
} // List[(Int, Int, Option[Long])]
// UPDATE Product AS p SET description = 'My Product', sku = 1011L WHERE p.id = 42
// RETURNING id + 100, myUdf(id), (SELECT MAX(s.id) FROM Supplier s WHERE s.sku = sku)

NOTE: Queries used inside of return clauses can only return a single row per insert. Otherwise, Postgres will throw: ERROR: more than one row returned by a subquery used as an expression. This is why is it strongly recommended that you use aggregators such as max or mininside of quill returning-clause queries. In the case that this is impossible (e.g. when using Postgres booleans), you can use the .value method: q.returning(r => query[Supplier].filter(s => s.sku == r.sku).map(_.id).value).

insert.returning

In certain situations we also may want to return information from inserted records.

val q = quote {
query[Product].insertValue(lift(Product(0, "My Product", 1011L))).returning(r => (id, description))
}

val returnedIds = ctx.run(q) //: List[(Int, String)]
// INSERT INTO Product (id, description, sku) VALUES (?, ?, ?) RETURNING id, description

Wait a second! Why did we just insert id into the database? That is because returning does not exclude values from the insertion! We can fix this situation by manually specifying the columns to insert:

val q = quote {
query[Product].insert(_.description -> "My Product", _.sku -> 1011L))).returning(r => (id, description))
}

val returnedIds = ctx.run(q) //: List[(Int, String)]
// INSERT INTO Product (description, sku) VALUES (?, ?) RETURNING id, description

We can also fix this situation by using an insert-meta.

implicit val productInsertMeta = insertMeta[Product](_.id)
val q = quote {
query[Product].insertValue(lift(Product(0L, "My Product", 1011L))).returning(r => (id, description))
}

val returnedIds = ctx.run(q) //: List[(Int, String)]
// INSERT INTO Product (description, sku) VALUES (?, ?) RETURNING id, description

Embedded case classes

Quill supports nested embedded case classes.

In previous iterations of Quill would need to extend the Embedded trait but this is no longer necessary.

final case class Contact(phone: String, address: String) /* The embedded class */
final case class Person(id: Int, name: String, contact: Contact)

ctx.run(query[Person])
// SELECT x.id, x.name, x.phone, x.address FROM Person x

Note that default naming behavior uses the name of the nested case class properties. It's possible to override this default behavior using a custom schema:

final case class Contact(phone: String, address: String) extends Embedded
final case class Person(id: Int, name: String, homeContact: Contact, workContact: Option[Contact])

val q = quote {
querySchema[Person](
"Person",
_.homeContact.phone -> "homePhone",
_.homeContact.address -> "homeAddress",
_.workContact.map(_.phone) -> "workPhone",
_.workContact.map(_.address) -> "workAddress"
)
}

ctx.run(q)
// SELECT x.id, x.name, x.homePhone, x.homeAddress, x.workPhone, x.workAddress FROM Person x

Queries

The overall abstraction of quill queries uses database tables as if they were in-memory collections. Scala for-comprehensions provide syntactic sugar to deal with these kinds of monadic operations:

final case class Person(id: Int, name: String, age: Int)
final case class Contact(personId: Int, phone: String)

val q = quote {
for {
p <- query[Person] if(p.id == 999)
c <- query[Contact] if(c.personId == p.id)
} yield {
(p.name, c.phone)
}
}

ctx.run(q)
// SELECT p.name, c.phone FROM Person p, Contact c WHERE (p.id = 999) AND (c.personId = p.id)

Quill normalizes the quotation and translates the monadic joins to applicative joins, generating a database-friendly query that avoids nested queries.

Any of the following features can be used together with the others and/or within a for-comprehension:

filter

val q = quote {
query[Person].filter(p => p.age > 18)
}

ctx.run(q)
// SELECT p.id, p.name, p.age FROM Person p WHERE p.age > 18

map

val q = quote {
query[Person].map(p => p.name)
}

ctx.run(q)
// SELECT p.name FROM Person p

flatMap

val q = quote {
query[Person].filter(p => p.age > 18).flatMap(p => query[Contact].filter(c => c.personId == p.id))
}

ctx.run(q)
// SELECT c.personId, c.phone FROM Person p, Contact c WHERE (p.age > 18) AND (c.personId = p.id)

sortBy

val q1 = quote {
query[Person].sortBy(p => p.age)
}

ctx.run(q1)
// SELECT p.id, p.name, p.age FROM Person p ORDER BY p.age ASC NULLS FIRST

val q2 = quote {
query[Person].sortBy(p => p.age)(Ord.descNullsLast)
}

ctx.run(q2)
// SELECT p.id, p.name, p.age FROM Person p ORDER BY p.age DESC NULLS LAST

val q3 = quote {
query[Person].sortBy(p => (p.name, p.age))(Ord(Ord.asc, Ord.desc))
}

ctx.run(q3)
// SELECT p.id, p.name, p.age FROM Person p ORDER BY p.name ASC, p.age DESC

aggregation

You can use aggregators inside of map-clauses. Multiple aggregators can be used as needed. Available aggregators are max, min, count, avg and sum.

val q = quote {
query[Person].map(p => (min(p.age), max(p.age)))
}
// SELECT MIN(p.age), MAX(p.age) FROM Person p

groupByMap

The groupByMap method is the preferred way to do grouping in Quill. It provides a simple aggregation-syntax similar to SQL. Available aggregators are max, min, count, avg and sum.

val q = quote {
query[Person].groupByMap(p => p.name)(p => (p.name, max(p.age)))
}
ctx.run(q)
// SELECT p.name, MAX(p.age) FROM Person p GROUP BY p.name

You can use as many aggregators as needed and group by multiple fields (using a Tuple).

val q = quote {
query[Person].groupByMap(p => (p.name, p.otherField))(p => (p.name, p.otherField, max(p.age)))
}
ctx.run(q)
// SELECT p.name, p.otherField, MAX(p.age) FROM Person p GROUP BY p.name, p.otherField

Writing a custom aggregator using infix with the groupByMax syntax is also very simple. For example, in Postgres the STRING_AGG function is used to concatenate all the encountered strings.

val stringAgg = quote {
(str: String, separator: String) => sql"STRING_AGG($str, $separator)".pure.as[String]
}
val q = quote {
query[Person].groupByMap(p => p.age)(p => (p.age, stringAgg(p.name, ";")))
}
run(q)
// SELECT p.age, STRING_AGG(p.name, ';') FROM Person p GROUP BY p.age

You can also map to a case class instead of a tuple. This will give you a Query[YourCaseClass] that you can further compose.

final case class NameAge(name: String, age: Int)
// Will return Query[NameAge]
val q = quote {
query[Person].groupByMap(p => p.name)(p => NameAge(p.name, max(p.age)))
}
ctx.run(q)
// SELECT p.name, MAX(p.age) FROM Person p GROUP BY p.name

Note that it is a requirement in SQL for every column in the selection (without an aggregator) to be in the GROUP BY clause. If it is not, an exception will be thrown by the database. Quill does not (yet!) protect the user in this situation.

run( query[Person].groupByMap(p => p.name)(p => (p.name, p.otherField, max(p.age))) )
// > SELECT p.name, p.otherField, MAX(p.age) FROM Person p GROUP BY p.name
// ERROR: column "person.otherField" must appear in the GROUP BY clause or be used in an aggregate function

groupBy

Quill also provides a way to do groupBy/map in a more scala-idiomatic way. In this case (below), the groupBy produces a Query[(Int,Query[Person])] where the inner Query can be mapped to an expression with an aggregator (as would be the Scala List[Person] in Map[Int,List[Person]] resulting from a (people:List[Person]).groupBy(_.name).

val q = quote {
query[Person].groupBy(p => p.age).map {
case (age, people) =>
(age, people.size)
}
}

ctx.run(q)
// SELECT p.age, COUNT(*) FROM Person p GROUP BY p.age

drop/take

val q = quote {
query[Person].drop(2).take(1)
}

ctx.run(q)
// SELECT x.id, x.name, x.age FROM Person x LIMIT 1 OFFSET 2

concatMap (i.e. UNNEST)

// similar to `flatMap` but for transformations that return a traversable instead of `Query`

val q = quote {
query[Person].concatMap(p => p.name.split(" "))
}

ctx.run(q)
// SELECT UNNEST(SPLIT(p.name, " ")) FROM Person p

union

val q = quote {
query[Person].filter(p => p.age > 18).union(query[Person].filter(p => p.age > 60))
}

ctx.run(q)
// SELECT x.id, x.name, x.age FROM (SELECT id, name, age FROM Person p WHERE p.age > 18
// UNION SELECT id, name, age FROM Person p1 WHERE p1.age > 60) x

unionAll/++

val q = quote {
query[Person].filter(p => p.age > 18).unionAll(query[Person].filter(p => p.age > 60))
}

ctx.run(q)
// SELECT x.id, x.name, x.age FROM (SELECT id, name, age FROM Person p WHERE p.age > 18
// UNION ALL SELECT id, name, age FROM Person p1 WHERE p1.age > 60) x

val q2 = quote {
query[Person].filter(p => p.age > 18) ++ query[Person].filter(p => p.age > 60)
}

ctx.run(q2)
// SELECT x.id, x.name, x.age FROM (SELECT id, name, age FROM Person p WHERE p.age > 18
// UNION ALL SELECT id, name, age FROM Person p1 WHERE p1.age > 60) x

aggregation

val r = quote {
query[Person].map(p => p.age)
}

ctx.run(r.min) // SELECT MIN(p.age) FROM Person p
ctx.run(r.max) // SELECT MAX(p.age) FROM Person p
ctx.run(r.avg) // SELECT AVG(p.age) FROM Person p
ctx.run(r.sum) // SELECT SUM(p.age) FROM Person p
ctx.run(r.size) // SELECT COUNT(p.age) FROM Person p

isEmpty/nonEmpty

val q = quote {
query[Person].filter{ p1 =>
query[Person].filter(p2 => p2.id != p1.id && p2.age == p1.age).isEmpty
}
}

ctx.run(q)
// SELECT p1.id, p1.name, p1.age FROM Person p1 WHERE
// NOT EXISTS (SELECT * FROM Person p2 WHERE (p2.id <> p1.id) AND (p2.age = p1.age))

val q2 = quote {
query[Person].filter{ p1 =>
query[Person].filter(p2 => p2.id != p1.id && p2.age == p1.age).nonEmpty
}
}

ctx.run(q2)
// SELECT p1.id, p1.name, p1.age FROM Person p1 WHERE
// EXISTS (SELECT * FROM Person p2 WHERE (p2.id <> p1.id) AND (p2.age = p1.age))

contains

val q = quote {
query[Person].filter(p => liftQuery(Set(1, 2)).contains(p.id))
}

ctx.run(q)
// SELECT p.id, p.name, p.age FROM Person p WHERE p.id IN (?, ?)

val q1 = quote { (ids: Query[Int]) =>
query[Person].filter(p => ids.contains(p.id))
}

ctx.run(q1(liftQuery(List(1, 2))))
// SELECT p.id, p.name, p.age FROM Person p WHERE p.id IN (?, ?)

val peopleWithContacts = quote {
query[Person].filter(p => query[Contact].filter(c => c.personId == p.id).nonEmpty)
}
val q2 = quote {
query[Person].filter(p => peopleWithContacts.contains(p.id))
}

ctx.run(q2)
// SELECT p.id, p.name, p.age FROM Person p WHERE p.id IN (SELECT p1.* FROM Person p1 WHERE EXISTS (SELECT c.* FROM Contact c WHERE c.personId = p1.id))

distinct

val q = quote {
query[Person].map(p => p.age).distinct
}

ctx.run(q)
// SELECT DISTINCT p.age FROM Person p

distinct on

Note that DISTINCT ON is currently only supported in Postgres and H2.

val q = quote {
query[Person].distinctOn(p => p.name)
}

ctx.run(q)
// SELECT DISTINCT ON (p.name) p.name, p.age FROM Person

Typically, DISTINCT ON is used with SORT BY.

val q = quote {
query[Person].distinctOn(p => p.name).sortBy(p => p.age)
}

ctx.run(q)
// SELECT DISTINCT ON (p.name) p.name, p.age FROM Person ORDER BY p.age ASC NULLS FIRST

You can also use multiple fields in the DISTINCT ON criteria:

// final case class Person(firstName: String, lastName: String, age: Int)
val q = quote {
query[Person].distinctOn(p => (p.firstName, p.lastName))
}

ctx.run(q)
// SELECT DISTINCT ON (p.firstName, p.lastName) p.firstName, p.lastName, p.age FROM Person p

nested

val q = quote {
query[Person].filter(p => p.name == "John").nested.map(p => p.age)
}

ctx.run(q)
// SELECT p.age FROM (SELECT p.age FROM Person p WHERE p.name = 'John') p

joins

Joins are arguably the largest source of complexity in most SQL queries. Quill offers a few different syntaxes so you can choose the right one for your use-case!

final case class A(id: Int)
final case class B(fk: Int)

// Applicative Joins:
quote {
query[A].join(query[B]).on(_.id == _.fk)
}

// Implicit Joins:
quote {
for {
a <- query[A]
b <- query[B] if (a.id == b.fk)
} yield (a, b)
}

// Flat Joins:
quote {
for {
a <- query[A]
b <- query[B].join(_.fk == a.id)
} yield (a, b)
}

Let's see them one by one assuming the following schema:

final case class Person(id: Int, name: String)
final case class Address(street: String, zip: Int, fk: Int)

(Note: If your use case involves lots and lots of joins, both inner and outer. Skip right to the flat-joins section!)

applicative joins

Applicative joins are useful for joining two tables together, they are straightforward to understand, and typically look good on one line. Quill supports inner, left-outer, right-outer, and full-outer (i.e. cross) applicative joins.

// Inner Join
val q = quote {
query[Person].join(query[Address]).on(_.id == _.fk)
}

ctx.run(q) //: List[(Person, Address)]
// SELECT x1.id, x1.name, x2.street, x2.zip, x2.fk
// FROM Person x1 INNER JOIN Address x2 ON x1.id = x2.fk

// Left (Outer) Join
val q = quote {
query[Person].leftJoin(query[Address]).on((p, a) => p.id == a.fk)
}

ctx.run(q) //: List[(Person, Option[Address])]
// Note that when you use named-variables in your comprehension, Quill does its best to honor them in the query.
// SELECT p.id, p.name, a.street, a.zip, a.fk
// FROM Person p LEFT JOIN Address a ON p.id = a.fk

// Right (Outer) Join
val q = quote {
query[Person].rightJoin(query[Address]).on((p, a) => p.id == a.fk)
}

ctx.run(q) //: List[(Option[Person], Address)]
// SELECT p.id, p.name, a.street, a.zip, a.fk
// FROM Person p RIGHT JOIN Address a ON p.id = a.fk

// Full (Outer) Join
val q = quote {
query[Person].fullJoin(query[Address]).on((p, a) => p.id == a.fk)
}

ctx.run(q) //: List[(Option[Person], Option[Address])]
// SELECT p.id, p.name, a.street, a.zip, a.fk
// FROM Person p FULL JOIN Address a ON p.id = a.fk

What about joining more than two tables with the applicative syntax? Here's how to do that:

final case class Company(zip: Int)

// All is well for two tables but for three or more, the nesting mess begins:
val q = quote {
query[Person]
.join(query[Address]).on({case (p, a) => p.id == a.fk}) // Let's use `case` here to stay consistent
.join(query[Company]).on({case ((p, a), c) => a.zip == c.zip})
}

ctx.run(q) //: List[((Person, Address), Company)]
// (Unfortunately when you use `case` statements, Quill can't help you with the variables names either!)
// SELECT x01.id, x01.name, x11.street, x11.zip, x11.fk, x12.name, x12.zip
// FROM Person x01 INNER JOIN Address x11 ON x01.id = x11.fk INNER JOIN Company x12 ON x11.zip = x12.zip

No worries though, implicit joins and flat joins have your other use-cases covered!

implicit joins

Quill's implicit joins use a monadic syntax making them pleasant to use for joining many tables together. They look a lot like Scala collections when used in for-comprehensions making them familiar to a typical Scala developer. What's the catch? They can only do inner-joins.

val q = quote {
for {
p <- query[Person]
a <- query[Address] if (p.id == a.fk)
} yield (p, a)
}

run(q) //: List[(Person, Address)]
// SELECT p.id, p.name, a.street, a.zip, a.fk
// FROM Person p, Address a WHERE p.id = a.fk

Now, this is great because you can keep adding more and more joins without having to do any pesky nesting.

val q = quote {
for {
p <- query[Person]
a <- query[Address] if (p.id == a.fk)
c <- query[Company] if (c.zip == a.zip)
} yield (p, a, c)
}

run(q) //: List[(Person, Address, Company)]
// SELECT p.id, p.name, a.street, a.zip, a.fk, c.name, c.zip
// FROM Person p, Address a, Company c WHERE p.id = a.fk AND c.zip = a.zip

Well that looks nice but wait! What If I need to inner, and outer join lots of tables nicely? No worries, flat-joins are here to help!

flat joins

Flat Joins give you the best of both worlds! In the monadic syntax, you can use both inner joins, and left-outer joins together without any of that pesky nesting.

// Inner Join
val q = quote {
for {
p <- query[Person]
a <- query[Address].join(a => a.fk == p.id)
} yield (p,a)
}

ctx.run(q) //: List[(Person, Address)]
// SELECT p.id, p.name, a.street, a.zip, a.fk
// FROM Person p INNER JOIN Address a ON a.fk = p.id

// Left (Outer) Join
val q = quote {
for {
p <- query[Person]
a <- query[Address].leftJoin(a => a.fk == p.id)
} yield (p,a)
}

ctx.run(q) //: List[(Person, Option[Address])]
// SELECT p.id, p.name, a.street, a.zip, a.fk
// FROM Person p LEFT JOIN Address a ON a.fk = p.id

Now you can keep adding both right and left joins without nesting!

val q = quote {
for {
p <- query[Person]
a <- query[Address].join(a => a.fk == p.id)
c <- query[Company].leftJoin(c => c.zip == a.zip)
} yield (p,a,c)
}

ctx.run(q) //: List[(Person, Address, Option[Company])]
// SELECT p.id, p.name, a.street, a.zip, a.fk, c.name, c.zip
// FROM Person p
// INNER JOIN Address a ON a.fk = p.id
// LEFT JOIN Company c ON c.zip = a.zip

Can't figure out what kind of join you want to use? Who says you have to choose?

With Quill the following multi-join queries are equivalent, use them according to preference:


final case class Employer(id: Int, personId: Int, name: String)

val qFlat = quote {
for{
(p,e) <- query[Person].join(query[Employer]).on(_.id == _.personId)
c <- query[Contact].leftJoin(_.personId == p.id)
} yield(p, e, c)
}

val qNested = quote {
for{
((p,e),c) <-
query[Person].join(query[Employer]).on(_.id == _.personId)
.leftJoin(query[Contact]).on(
_._1.id == _.personId
)
} yield(p, e, c)
}

ctx.run(qFlat)
ctx.run(qNested)
// SELECT p.id, p.name, p.age, e.id, e.personId, e.name, c.id, c.phone
// FROM Person p INNER JOIN Employer e ON p.id = e.personId LEFT JOIN Contact c ON c.personId = p.id

Note that in some cases implicit and flat joins cannot be used together, for example, the following query will fail.

val q = quote {
for {
p <- query[Person]
p1 <- query[Person] if (p1.name == p.name)
c <- query[Contact].leftJoin(_.personId == p.id)
} yield (p, c)
}

// ctx.run(q)
// java.lang.IllegalArgumentException: requirement failed: Found an `ON` table reference of a table that is
// not available: Set(p). The `ON` condition can only use tables defined through explicit joins.

This happens because an explicit join typically cannot be done after an implicit join in the same query.

A good guideline is in any query or subquery, choose one of the following:

  • Use flat-joins + applicative joins or
  • Use implicit joins

Also, note that not all Option operations are available on outer-joined tables (i.e. tables wrapped in an Option object), only a specific subset. This is mostly due to the inherent limitations of SQL itself. For more information, see the 'Optional Tables' section.

Optionals / Nullable Fields

Note that the behavior of Optionals has recently changed to include stricter null-checks. See the orNull / getOrNull section for more details.

Option objects are used to encode nullable fields. Say you have the following schema:

CREATE TABLE Person(
id INT NOT NULL PRIMARY KEY,
name VARCHAR(255) -- This is nullable!
);
CREATE TABLE Address(
fk INT, -- This is nullable!
street VARCHAR(255) NOT NULL,
zip INT NOT NULL,
CONSTRAINT a_to_p FOREIGN KEY (fk) REFERENCES Person(id)
);
CREATE TABLE Company(
name VARCHAR(255) NOT NULL,
zip INT NOT NULL
)

This would encode to the following:

final case class Person(id:Int, name:Option[String])
final case class Address(fk:Option[Int], street:String, zip:Int)
final case class Company(name:String, zip:Int)

Some important notes regarding Optionals and nullable fields.

In many cases, Quill tries to rely on the null-fallthrough behavior that is ANSI standard:

  • null == null := false
  • null == [true | false] := false

This allows the generated SQL for most optional operations to be simple. For example, the expression Option[String].map(v => v + "foo") can be expressed as the SQL v || 'foo' as opposed to CASE IF (v is not null) v || 'foo' ELSE null END so long as the concatenation operator || "falls-through" and returns null when the input is null. This is not true of all databases (e.g. Oracle), forcing Quill to return the longer expression with explicit null-checking. Also, if there are conditionals inside of an Option operation (e.g. o.map(v => if (v == "x") "y" else "z")) this creates SQL with case statements, which will never fall-through when the input value is null. This forces Quill to explicitly null-check such statements in every SQL dialect.

Let's go through the typical operations of optionals.

isDefined / isEmpty

The isDefined method is generally a good way to null-check a nullable field:

val q = quote {
query[Address].filter(a => a.fk.isDefined)
}
ctx.run(q)
// SELECT a.fk, a.street, a.zip FROM Address a WHERE a.fk IS NOT NULL

The isEmpty method works the same way:

val q = quote {
query[Address].filter(a => a.fk.isEmpty)
}
ctx.run(q)
// SELECT a.fk, a.street, a.zip FROM Address a WHERE a.fk IS NULL

exists

This method is typically used for inspecting nullable fields inside of boolean conditions, most notably joining!

val q = quote {
query[Person].join(query[Address]).on((p, a)=> a.fk.exists(_ == p.id))
}
ctx.run(q)
// SELECT p.id, p.name, a.fk, a.street, a.zip FROM Person p INNER JOIN Address a ON a.fk = p.id

Note that in the example above, the exists method does not cause the generated SQL to do an explicit null-check in order to express the False case. This is because Quill relies on the typical database behavior of immediately falsifying a statement that has null on one side of the equation.

forall

Use this method in boolean conditions that should succeed in the null case.

val q = quote {
query[Person].join(query[Address]).on((p, a) => a.fk.forall(_ == p.id))
}
ctx.run(q)
// SELECT p.id, p.name, a.fk, a.street, a.zip FROM Person p INNER JOIN Address a ON a.fk IS NULL OR a.fk = p.id

Typically this is useful when doing negative conditions, e.g. when a field is not some specified value (e.g. "Joe"). Being null in this case is typically a matching result.

val q = quote {
query[Person].filter(p => p.name.forall(_ != "Joe"))
}

ctx.run(q)
// SELECT p.id, p.name FROM Person p WHERE p.name IS NULL OR p.name <> 'Joe'

filterIfDefined

Use this to filter by a optional field that you want to ignore when None. This is useful when you want to filter by a map-key that may or may not exist.

val fieldFilters: Map[String, String] = Map("name" -> "Joe", "age" -> "123")
val q = quote {
query[Person].filter(p => lift(fieldFilters.get("name)).filterIfDefined(_ == p.name))
}

ctx.run(q)
// SELECT p.id, p.name, p.title FROM Person p WHERE p.title IS NULL OR p.title = 'The Honorable'

It also works for regular fields.

// final case class Person(name: String, age: Int, title: Option[String])
val q = quote {
query[Person].filter(p => p.title.filterIfDefined(_ == "The Honorable"))
}

ctx.run(q)
// SELECT p.id, p.name, p.title FROM Person p WHERE p.title IS NULL OR p.title = 'The Honorable'

map

As in regular Scala code, performing any operation on an optional value typically requires using the map function.

val q = quote {
for {
p <- query[Person]
} yield (p.id, p.name.map("Dear " + _))
}

ctx.run(q)
// SELECT p.id, 'Dear ' || p.name FROM Person p
// * In Dialects where `||` does not fall-through for nulls (e.g. Oracle):
// * SELECT p.id, CASE WHEN p.name IS NOT NULL THEN 'Dear ' || p.name ELSE null END FROM Person p

Additionally, this method is useful when you want to get a non-optional field out of an outer-joined table (i.e. a table wrapped in an Option object).

val q = quote {
query[Company].leftJoin(query[Address])
.on((c, a) => c.zip == a.zip)
.map {case(c,a) => // Row type is (Company, Option[Address])
(c.name, a.map(_.street), a.map(_.zip)) // Use `Option.map` to get `street` and `zip` fields
}
}

run(q)
// SELECT c.name, a.street, a.zip FROM Company c LEFT JOIN Address a ON c.zip = a.zip

For more details about this operation (and some caveats), see the 'Optional Tables' section.

flatMap and flatten

Use these when the Option.map functionality is not sufficient. This typically happens when you need to manipulate multiple nullable fields in a way which would otherwise result in Option[Option[T]].

val q = quote {
for {
a <- query[Person]
b <- query[Person] if (a.id > b.id)
} yield (
// If this was `a.name.map`, resulting record type would be Option[Option[String]]
a.name.flatMap(an =>
b.name.map(bn =>
an+" comes after "+bn)))
}

ctx.run(q) //: List[Option[String]]
// SELECT (a.name || ' comes after ') || b.name FROM Person a, Person b WHERE a.id > b.id
// * In Dialects where `||` does not fall-through for nulls (e.g. Oracle):
// * SELECT CASE WHEN a.name IS NOT NULL AND b.name IS NOT NULL THEN (a.name || ' comes after ') || b.name ELSE null END FROM Person a, Person b WHERE a.id > b.id

// Alternatively, you can use `flatten`
val q = quote {
for {
a <- query[Person]
b <- query[Person] if (a.id > b.id)
} yield (
a.name.map(an =>
b.name.map(bn =>
an + " comes after " + bn)).flatten)
}

ctx.run(q) //: List[Option[String]]
// SELECT (a.name || ' comes after ') || b.name FROM Person a, Person b WHERE a.id > b.id

This is also very useful when selecting from outer-joined tables i.e. where the entire table is inside of an Option object. Note how below we get the fk field from Option[Address].

val q = quote {
query[Person].leftJoin(query[Address])
.on((p, a) => a.fk.exists(_ == p.id))
.map {case (p /*Person*/, a /*Option[Address]*/) => (p.name, a.flatMap(_.fk))}
}

ctx.run(q) //: List[(Option[String], Option[Int])]
// SELECT p.name, a.fk FROM Person p LEFT JOIN Address a ON a.fk = p.id

orNull / getOrNull

The orNull method can be used to convert an Option-enclosed row back into a regular row. Since Option[T].orNull does not work for primitive types (e.g. Int, Double, etc...), you can use the getOrNull method inside of quoted blocks to do the same thing.

Note that since the presence of null columns can cause queries to break in some data sources (e.g. Spark), so use this operation very carefully.

val q = quote {
query[Person].join(query[Address])
.on((p, a) => a.fk.exists(_ == p.id))
.filter {case (p /*Person*/, a /*Option[Address]*/) =>
a.fk.getOrNull != 123 } // Exclude a particular value from the query.
// Since we already did an inner-join on this value, we know it is not null.
}

ctx.run(q) //: List[(Address, Person)]
// SELECT p.id, p.name, a.fk, a.street, a.zip FROM Person p INNER JOIN Address a ON a.fk IS NOT NULL AND a.fk = p.id WHERE a.fk <> 123

In certain situations, you may wish to pretend that a nullable-field is not actually nullable and perform regular operations (e.g. arithmetic, concatenation, etc...) on the field. You can use a combination of Option.apply and orNull (or getOrNull where needed) in order to do this.

val q = quote {
query[Person].map(p => Option(p.name.orNull + " suffix"))
}

ctx.run(q)
// SELECT p.name || ' suffix' FROM Person p
// i.e. same as the previous behavior

In all other situations, since Quill strictly checks nullable values, and case.. if conditionals will work correctly in all Optional constructs. However, since they may introduce behavior changes in your codebase, the following warning has been introduced:

Conditionals inside of Option.[map | flatMap | exists | forall] will create a CASE statement in order to properly null-check the sub-query (...)

val q = quote {
query[Person].map(p => p.name.map(n => if (n == "Joe") "foo" else "bar").getOrElse("baz"))
}
// Information:(16, 15) Conditionals inside of Option.map will create a `CASE` statement in order to properly null-check the sub-query: `p.name.map((n) => if(n == "Joe") "foo" else "bar")`.
// Expressions like Option(if (v == "foo") else "bar").getOrElse("baz") will now work correctly, but expressions that relied on the broken behavior (where "bar" would be returned instead) need to be modified (see the "orNull / getOrNull" section of the documentation of more detail).

ctx.run(a)
// Used to be this:
// SELECT CASE WHEN CASE WHEN p.name = 'Joe' THEN 'foo' ELSE 'bar' END IS NOT NULL THEN CASE WHEN p.name = 'Joe' THEN 'foo' ELSE 'bar' END ELSE 'baz' END FROM Person p
// Now is this:
// SELECT CASE WHEN p.name IS NOT NULL AND CASE WHEN p.name = 'Joe' THEN 'foo' ELSE 'bar' END IS NOT NULL THEN CASE WHEN p.name = 'Joe' THEN 'foo' ELSE 'bar' END ELSE 'baz' END FROM Person p

equals

The ==, !=, and .equals methods can be used to compare regular types as well Option types in a scala-idiomatic way. That is to say, either T == T or Option[T] == Option[T] is supported and the following "truth-table" is observed:

LeftRightEqualityResult
ab==a == b
Some[T](a)Some[T](b)==a == b
Some[T](a)None==false
None Some[T](b)==false
None None==true
Some[T] Some[R] ==Exception thrown.
ab!=a != b
Some[T](a)Some[T](b)!=a != b
Some[T](a)None!=true
None Some[T](b)!=true
Some[T] Some[R] !=Exception thrown.
None None!=false
final case class Node(id:Int, status:Option[String], otherStatus:Option[String])

val q = quote { query[Node].filter(n => n.id == 123) }
ctx.run(q)
// SELECT n.id, n.status, n.otherStatus FROM Node n WHERE p.id = 123

val q = quote { query[Node].filter(r => r.status == r.otherStatus) }
ctx.run(q)
// SELECT r.id, r.status, r.otherStatus FROM Node r WHERE r.status IS NULL AND r.otherStatus IS NULL OR r.status = r.otherStatus

val q = quote { query[Node].filter(n => n.status == Option("RUNNING")) }
ctx.run(q)
// SELECT n.id, n.status, n.otherStatus FROM node n WHERE n.status IS NOT NULL AND n.status = 'RUNNING'

val q = quote { query[Node].filter(n => n.status != Option("RUNNING")) }
ctx.run(q)
// SELECT n.id, n.status, n.otherStatus FROM node n WHERE n.status IS NULL OR n.status <> 'RUNNING'

If you would like to use an equality operator that follows that ansi-idiomatic approach, failing the comparison if either side is null as well as the principle that null = null := false, you can import === (and =!=) from Context.extras. These operators work across T and Option[T] allowing comparisons like T === Option[T], Option[T] == T etc... to be made. You can use also === directly in Scala code and it will have the same behavior, returning false when other the left-hand or right-hand side is None. This is particularity useful in paradigms like Spark where you will typically transition inside and outside of Quill code.

When using a === b or a =!= b sometimes you will see the extra a IS NOT NULL AND b IS NOT NULL comparisons and sometimes you will not. This depends on equalityBehavior in SqlIdiom which determines whether the given SQL dialect already does ansi-idiomatic comparison to a, and b when an = operator is used, this allows us to omit the extra a IS NOT NULL AND b IS NOT NULL.

import ctx.extras._

// === works the same way inside of a quotation
val q = run( query[Node].filter(n => n.status === "RUNNING") )
// SELECT n.id, n.status FROM node n WHERE n.status IS NOT NULL AND n.status = 'RUNNING'

// as well as outside
(nodes:List[Node]).filter(n => n.status === "RUNNING")

Optional Tables

As we have seen in the examples above, only the map and flatMap methods are available on outer-joined tables (i.e. tables wrapped in an Option object).

Since you cannot use Option[Table].isDefined, if you want to null-check a whole table (e.g. if a left-join was not matched), you have to map to a specific field on which you can do the null-check.

val q = quote {
query[Company].leftJoin(query[Address])
.on((c, a) => c.zip == a.zip) // Row type is (Company, Option[Address])
.filter({case(c,a) => a.isDefined}) // You cannot null-check a whole table!
}

Instead, map the row-variable to a specific field and then check that field.

val q = quote {
query[Company].leftJoin(query[Address])
.on((c, a) => c.zip == a.zip) // Row type is (Company, Option[Address])
.filter({case(c,a) => a.map(_.street).isDefined}) // Null-check a non-nullable field instead
}
ctx.run(q)
// SELECT c.name, c.zip, a.fk, a.street, a.zip
// FROM Company c
// LEFT JOIN Address a ON c.zip = a.zip
// WHERE a.street IS NOT NULL

Finally, it is worth noting that a whole table can be wrapped into an Option object. This is particularly useful when doing a union on table-sets that are both right-joined and left-joined together.

val aCompanies = quote {
for {
c <- query[Company] if (c.name like "A%")
a <- query[Address].join(_.zip == c.zip)
} yield (c, Option(a)) // change (Company, Address) to (Company, Option[Address])
}
val bCompanies = quote {
for {
c <- query[Company] if (c.name like "A%")
a <- query[Address].leftJoin(_.zip == c.zip)
} yield (c, a) // (Company, Option[Address])
}
val union = quote {
aCompanies union bCompanies
}
ctx.run(union)
// SELECT x.name, x.zip, x.fk, x.street, x.zip FROM (
// (SELECT c.name name, c.zip zip, x1.zip zip, x1.fk fk, x1.street street
// FROM Company c INNER JOIN Address x1 ON x1.zip = c.zip WHERE c.name like 'A%')
// UNION
// (SELECT c1.name name, c1.zip zip, x2.zip zip, x2.fk fk, x2.street street
// FROM Company c1 LEFT JOIN Address x2 ON x2.zip = c1.zip WHERE c1.name like 'A%')
// ) x

Ad-Hoc Case Classes

Case Classes can also be used inside quotations as output values:

final case class Person(id: Int, name: String, age: Int)
final case class Contact(personId: Int, phone: String)
final case class ReachablePerson(name:String, phone: String)

val q = quote {
for {
p <- query[Person] if(p.id == 999)
c <- query[Contact] if(c.personId == p.id)
} yield {
ReachablePerson(p.name, c.phone)
}
}

ctx.run(q)
// SELECT p.name, c.phone FROM Person p, Contact c WHERE (p.id = 999) AND (c.personId = p.id)

As well as in general:

final case class IdFilter(id:Int)

val q = quote {
val idFilter = new IdFilter(999)
for {
p <- query[Person] if(p.id == idFilter.id)
c <- query[Contact] if(c.personId == p.id)
} yield {
ReachablePerson(p.name, c.phone)
}
}

ctx.run(q)
// SELECT p.name, c.phone FROM Person p, Contact c WHERE (p.id = 999) AND (c.personId = p.id)

Note however that this functionality has the following restrictions:

  1. The Ad-Hoc Case Class can only have one constructor with one set of parameters.
  2. The Ad-Hoc Case Class must be constructed inside the quotation using one of the following methods:
    1. Using the new keyword: new Person("Joe", "Bloggs")
    2. Using a companion object's apply method: Person("Joe", "Bloggs")
    3. Using a companion object's apply method explicitly: Person.apply("Joe", "Bloggs")
  3. Any custom logic in a constructor/apply-method of an Ad-Hoc case class will not be invoked when it is 'constructed' inside a quotation. To construct an Ad-Hoc case class with custom logic inside a quotation, you can use a quoted method.

Query probing

Query probing validates queries against the database at compile time, failing the compilation if it is not valid. The query validation does not alter the database state.

This feature is disabled by default. To enable it, mix the QueryProbing trait to the database configuration:

object myContext extends YourContextType with QueryProbing

The context must be created in a separate compilation unit in order to be loaded at compile time. Please use this guide that explains how to create a separate compilation unit for macros, that also serves to the purpose of defining a query-probing-capable context. context could be used instead of macros as the name of the separate compilation unit.

The configurations correspondent to the config key must be available at compile time. You can achieve it by adding this line to your project settings:

unmanagedClasspath in Compile += baseDirectory.value / "src" / "main" / "resources"

If your project doesn't have a standard layout, e.g. a play project, you should configure the path to point to the folder that contains your config file.

Actions

Database actions are defined using quotations as well. These actions don't have a collection-like API but rather a custom DSL to express inserts, deletes, and updates.

insertValue / insert

val a = quote(query[Contact].insertValue(lift(Contact(999, "+1510488988"))))

ctx.run(a) // = 1 if the row was inserted 0 otherwise
// INSERT INTO Contact (personId,phone) VALUES (?, ?)

It is also possible to insert specific columns (via insert):

val a = quote {
query[Contact].insert(_.personId -> lift(999), _.phone -> lift("+1510488988"))
}

ctx.run(a)
// INSERT INTO Contact (personId,phone) VALUES (?, ?)

batch insert

val a = quote {
liftQuery(List(Person(0, "John", 31),Person(2, "name2", 32))).foreach(e => query[Person].insertValue(e))
}

ctx.run(a) //: List[Long] size = 2. Contains 1 @ positions, where row was inserted E.g List(1,1)
// INSERT INTO Person (id,name,age) VALUES (?, ?, ?)

In addition to regular JDBC batching, Quill can optimize batch queries by using multiple VALUES-clauses e.g:

ctx.run(a, 2)
// INSERT INTO Person (id,name,age) VALUES (?, ?, ?), (?, ?, ?) // Note, the extract (?, ?, ?) will not be visible in the compiler output.

In situations with high network latency this can improve performance by 20-40x! See the Batch Optimization below for more info.

Just as in regular queries use the extended insert/update syntaxes to achieve finer-grained control of the data being created/modified modified. For example, if the ID is a generated value you can skip ID insertion like this: (This can also be accomplished with an insert-meta).

// final case class Person(id: Int, name: String, age: Int)
val a = quote {
liftQuery(List(Person(0, "John", 31),Person(0, "name2", 32))).foreach(e => query[Person].insert(_.name -> p.name, _.age -> p.age))
}

ctx.run(a)
// INSERT INTO Person (name,age) VALUES (?, ?)

Batch queries can also have a returning/returningGenerated clause:

// final case class Person(id: Int, name: String, age: Int)
val a = quote {
liftQuery(List(Person(0, "John", 31),Person(0, "name2", 32))).foreach(e => query[Person].insert(_.name -> p.name, _.age -> p.age)).returning(_.id)
}

ctx.run(a)
// INSERT INTO Person (name,age) VALUES (?, ?) RETURNING id

Note that the liftQuery[Something] and the query[Something]` values do not necessarily need to be the same object-type. (In fact the liftQuery value can even be a constant!) For example:

// final case class Person(name: String, age: Int)
// final case class Vip(first: String, last: String, age: Int)
// val vips: List[Vip] = ...
val q = quote {
liftQuery(vips).foreach(v => query[Person].insertValue(Person(v.first + v.last, v.age)))
}

ctx.run(q)
// INSERT INTO Person (name,age) VALUES ((? || ?), ?)

Note that UPDATE queries can also be done in batches (as well as DELETE queries).

val q = quote {
liftQuery(vips).foreach(v => query[Person].filter(p => p.age > 22).updateValue(Person(v.first + v.last, v.age)))
}

ctx.run(q)
// UPDATE Person SET name = (? || ?), age = ? WHERE age > 22

updateValue / update

val a = quote {
query[Person].filter(_.id == 999).updateValue(lift(Person(999, "John", 22)))
}

ctx.run(a) // = Long number of rows updated
// UPDATE Person SET id = ?, name = ?, age = ? WHERE id = 999

Using specific columns (via update):

val a = quote {
query[Person].filter(p => p.id == lift(999)).update(_.age -> lift(18))
}

ctx.run(a)
// UPDATE Person SET age = ? WHERE id = ?

Using columns as part of the update:

val a = quote {
query[Person].filter(p => p.id == lift(999)).update(p => p.age -> (p.age + 1))
}

ctx.run(a)
// UPDATE Person SET age = (age + 1) WHERE id = ?

batch update

val a = quote {
liftQuery(List(Person(1, "name", 31),Person(2, "name2", 32))).foreach { person =>
query[Person].filter(_.id == person.id).update(_.name -> person.name, _.age -> person.age)
}
}

ctx.run(a) // : List[Long] size = 2. Contains 1 @ positions, where row was inserted E.g List(1,0)
// UPDATE Person SET name = ?, age = ? WHERE id = ?

delete

val a = quote {
query[Person].filter(p => p.name == "").delete
}

ctx.run(a) // = Long the number of rows deleted
// DELETE FROM Person WHERE name = ''

insert or update (upsert, conflict)

Upsert is supported by Postgres, SQLite, MySQL and H2 onConflictIgnore only (since v1.4.200 in PostgreSQL compatibility mode)

Postgres and SQLite

Ignore conflict
val a = quote {
query[Product].insert(_.id -> 1, _.sku -> 10).onConflictIgnore
}

// INSERT INTO Product AS t (id,sku) VALUES (1, 10) ON CONFLICT DO NOTHING

Ignore conflict by explicitly setting conflict target

val a = quote {
query[Product].insert(_.id -> 1, _.sku -> 10).onConflictIgnore(_.id)
}

// INSERT INTO Product AS t (id,sku) VALUES (1, 10) ON CONFLICT (id) DO NOTHING

Multiple properties can be used as well.

val a = quote {
query[Product].insert(_.id -> 1, _.sku -> 10).onConflictIgnore(_.id, _.description)
}

// INSERT INTO Product (id,sku) VALUES (1, 10) ON CONFLICT (id,description) DO NOTHING
Update on Conflict

Resolve conflict by updating existing row if needed. In onConflictUpdate(target)((t, e) => assignment): target refers to conflict target, t - to existing row and e - to excluded, e.g. row proposed for insert.

val a = quote {
query[Product]
.insert(_.id -> 1, _.sku -> 10)
.onConflictUpdate(_.id)((t, e) => t.sku -> (t.sku + e.sku))
}

// INSERT INTO Product AS t (id,sku) VALUES (1, 10) ON CONFLICT (id) DO UPDATE SET sku = (t.sku + EXCLUDED.sku)

Multiple properties can be used with onConflictUpdate as well.

val a = quote {
query[Product]
.insert(_.id -> 1, _.sku -> 10)
.onConflictUpdate(_.id, _.description)((t, e) => t.sku -> (t.sku + e.sku))
}

INSERT INTO Product AS t (id,sku) VALUES (1, 10) ON CONFLICT (id,description) DO UPDATE SET sku = (t.sku + EXCLUDED.sku)

MySQL

Ignore any conflict, e.g. insert ignore

val a = quote {
query[Product].insert(_.id -> 1, _.sku -> 10).onConflictIgnore
}

// INSERT IGNORE INTO Product (id,sku) VALUES (1, 10)

Ignore duplicate key conflict by explicitly setting it

val a = quote {
query[Product].insert(_.id -> 1, _.sku -> 10).onConflictIgnore(_.id)
}

// INSERT INTO Product (id,sku) VALUES (1, 10) ON DUPLICATE KEY UPDATE id=id

Resolve duplicate key by updating existing row if needed. In onConflictUpdate((t, e) => assignment): t refers to existing row and e - to values, e.g. values proposed for insert.

val a = quote {
query[Product]
.insert(_.id -> 1, _.sku -> 10)
.onConflictUpdate((t, e) => t.sku -> (t.sku + e.sku))
}

// INSERT INTO Product (id,sku) VALUES (1, 10) ON DUPLICATE KEY UPDATE sku = (sku + VALUES(sku))

Batch Optimization

When doing batch INSERT queries (as well as UPDATE, and DELETE), Quill mostly delegates the functionality to standard JDBC batching. This functionality works roughly in the following way.

val ps: PreparedStatement = connection.prepareStatement("INSERT ... VALUES ...")
// 1. Iterate over the rows
for (row <- rowsToInsert) {
// 2. For each row, add the columns to the prepared statement
for ((column, columnIndex) <- row)
row.setColumn(column, columnIndex)
// 3. Add the row to the list of things being added in the batch
ps.addBatch()
}
// 4. Write everything in the batch to the Database
ps.executeBatch()

Reasonably speaking, we would expect each call in Stage #3 to locally stage the value of the row and then submit all of the rows to the database in Stage #4 but that basically every database that is not what happens. In Stage #3, a network call is actually made to the Database to remotely stage the row. Practically this means that the performance of addBatch/executeBatch degrades per-row, per-millisecond-network-latency. Even at 50 milliseconds of network latency the impact of this is highly significant:

Network LatencyRows InsertedTotal Time
0ms10k rows0.486
50ms10k rows3.226
100ms10k rows5.266
0ms100k rows1.416
50ms100k rows23.248
100ms100k rows43.077
0ms1m rows13.616
50ms1m rows234.452
100ms1m rows406.101

In order to alleviate this problem Quill can take advantage of the ability of most database dialects to use multiple VALUES-clauses to batch-insert rows. Conceptually, this works in the following way:

final case class Person(name: String, age: Int)
val people = List(Person("Joe", 22), Person("Jack", 33), Person("Jill", 44))
val q = quote { liftQuery(people).foreach(p => query[Person].insertValue(p)) }
run(q, 2) // i.e. insert rows from the `people` list in batches of 2
//
// Query1) INSERT INTO Person (name, age) VALUES ([Joe] , [22]), ([Jack], [33])
// INSERT INTO Person (name, age) VALUES ( ? , ? ), ( ? , ? ) <- actual query
// Query2) INSERT INTO Person (name, age) VALUES ([Jill], [44])
// INSERT INTO Person (name, age) VALUES ( ? , ? ) <- actual query

Note that only INSERT INTO Person (name, age) VALUES (?, ?) will appear in the compiler-output for this query!

Using a batch-count of about 1000-5000 rows (i.e. run(q, 1000)) can significantly improve query performance:

Network LatencyRows InsertedTotal Time
0ms10k rows3.772
50ms10k rows3.899
100ms10k rows4.63
0ms100k rows2.902
50ms100k rows3.225
100ms100k rows3.554
0ms1m rows9.923
50ms1m rows10.035
100ms1m rows10.328

One thing to take note of is that each one of the ? placeholders above is a prepared-statement variable. This means that in batch-sizes of 1000, there will be 1000 ? variables in each query. In many databases this has a strict limit. For example, in Postgres this is restricted to 32767. This means that when using batches of 1000 rows, each row can have up to 32 columns or the following error will occur:

IOException: Tried to send an out-of-range integer as a 2-byte value

In other database e.g. SQL Server, unfortunately this limit is much smaller. For example in SQL Server it is just 2100 variables or the following error will occur.

The server supports a maximum of 2100 parameters. Reduce the number of parameters and resend the request

This means that in SQL Server, for a batch-size of 100, you can only insert into a table of up to 21 columns.

In the future, we hope to alleviate this issue by directly substituting variables into ? variables before the query is executed however such functionality could potentially come at the risk of SQL-injection vulnerabilities.

Printing Queries

The translate method is used to convert a Quill query into a string which can then be printed.

val str = ctx.translate(query[Person])
println(str)
// SELECT x.id, x.name, x.age FROM Person x

Insert queries can also be printed:

val str = ctx.translate(query[Person].insertValue(lift(Person(0, "Joe", 45))))
println(str)
// INSERT INTO Person (id,name,age) VALUES (0, 'Joe', 45)

As well as batch insertions:

val q = quote {
liftQuery(List(Person(0, "Joe",44), Person(1, "Jack",45)))
.foreach(e => query[Person].insertValue(e))
}
val strs: List[String] = ctx.translate(q)
strs.map(println)
// INSERT INTO Person (id, name,age) VALUES (0, 'Joe', 44)
// INSERT INTO Person (id, name,age) VALUES (1, 'Jack', 45)

The translate method is available in every Quill context as well as the Cassandra and OrientDB contexts, the latter two, however, do not support Insert and Batch Insert query printing.

IO Monad

Quill provides an IO monad that allows the user to express multiple computations and execute them separately. This mechanism is also known as a free monad, which provides a way of expressing computations as referentially-transparent values and isolates the unsafe IO operations into a single operation. For instance:

// this code using Future

final case class Person(id: Int, name: String, age: Int)

val p = Person(0, "John", 22)
ctx.run(query[Person].insertValue(lift(p))).flatMap { _ =>
ctx.run(query[Person])
}

// isn't referentially transparent because if you refactor the second database
// interaction into a value, the result will be different:

val allPeople = ctx.run(query[Person])
ctx.run(query[Person].insertValue(lift(p))).flatMap { _ =>
allPeople
}

// this happens because `ctx.run` executes the side-effect (database IO) immediately
// The IO monad doesn't perform IO immediately, so both computations:

val p = Person(0, "John", 22)

val a =
ctx.runIO(query[Person].insertValue(lift(p))).flatMap { _ =>
ctx.runIO(query[Person])
}


val allPeople = ctx.runIO(query[Person])

val b =
ctx.runIO(query[Person].insertValue(lift(p))).flatMap { _ =>
allPeople
}

// produce the same result when executed

performIO(a) == performIO(b)

The IO monad has an interface similar to Future; please refer to the class for more information regarding the available operations.

The return type of performIO varies according to the context. For instance, async contexts return Futures while JDBC returns values synchronously.

NOTE: Avoid using the variable name io since it conflicts with Quill's package io.getquill, otherwise you will get the following error.

recursive value io needs type

IO Monad and transactions

IO also provides the transactional method that delimits a transaction:

val a =
ctx.runIO(query[Person].insertValue(lift(p))).flatMap { _ =>
ctx.runIO(query[Person])
}

performIO(a.transactional) // note: transactional can be used outside of `performIO`

Getting a ResultSet

Quill JDBC Contexts allow you to use prepare in order to get a low-level ResultSet that is useful for interacting with legacy APIs. This function returns a f: (Connection) => (PreparedStatement) closure as opposed to a PreparedStatement in order to guarantee that JDBC Exceptions are not thrown until you can wrap them into the appropriate Exception-handling mechanism (e.g. try/catch, Try etc...).

val q = quote {
query[Product].filter(_.id == 1)
}
val preparer: (Connection) => (PreparedStatement) = ctx.prepare(q)
// SELECT x1.id, x1.description, x1.sku FROM Product x1 WHERE x1.id = 1

// Use ugly stateful code, bracketed effects, or try-with-resources here:
var preparedStatement: PreparedStatement = _
var resultSet: ResultSet = _

try {
preparedStatement = preparer(myCustomDataSource.getConnection)
resultSet = preparedStatement.executeQuery()
} catch {
case e: Exception =>
// Close the preparedStatement and catch possible exceptions
// Close the resultSet and catch possible exceptions
}

The prepare function can also be used with insertValue, and updateValue actions.

val q = quote {
query[Product].insertValue(lift(Product(1, "Desc", 123))
}
val preparer: (Connection) => (PreparedStatement) = ctx.prepare(q)
// INSERT INTO Product (id,description,sku) VALUES (?, ?, ?)

As well as with batch queries.

Make sure to first quote your batch query and then pass the result into the prepare function (as is done in the example below) or the Scala compiler may not type the output correctly #1518.

val q = quote {
liftQuery(products).foreach(e => query[Product].insertValue(e))
}
val preparers: Connection => List[PreparedStatement] = ctx.prepare(q)
val preparedStatement: List[PreparedStatement] = preparers(jdbcConf.dataSource.getConnection)

Effect tracking

The IO monad tracks the effects that a computation performs in its second type parameter:

val a: IO[ctx.RunQueryResult[Person], Effect.Write with Effect.Read] =
ctx.runIO(query[Person].insertValue(lift(p))).flatMap { _ =>
ctx.runIO(query[Person])
}

This mechanism is useful to limit the kind of operations that can be performed. See this blog post as an example.

Implicit query

Quill provides implicit conversions from case class companion objects to query[T] through an additional trait:

val ctx = new SqlMirrorContext(MirrorSqlDialect, Literal) with ImplicitQuery

import ctx._

val q = quote {
for {
p <- Person if(p.id == 999)
c <- Contact if(c.personId == p.id)
} yield {
(p.name, c.phone)
}
}

ctx.run(q)
// SELECT p.name, c.phone FROM Person p, Contact c WHERE (p.id = 999) AND (c.personId = p.id)

Note the usage of Person and Contact instead of query[Person] and query[Contact].

SQL-specific operations

Some operations are SQL-specific and not provided with the generic quotation mechanism. The SQL contexts provide implicit classes for this kind of operation:

val ctx = new SqlMirrorContext(MirrorSqlDialect, Literal)
import ctx._

like

val q = quote {
query[Person].filter(p => p.name like "%John%")
}
ctx.run(q)
// SELECT p.id, p.name, p.age FROM Person p WHERE p.name like '%John%'

forUpdate

val q = quote {
query[Person].filter(p => p.name == "Mary").forUpdate()
}
ctx.run(q)
// SELECT p.id, p.name, p.age FROM Person p WHERE p.name = 'Mary' FOR UPDATE

SQL-specific encoding

Arrays

Quill provides SQL Arrays support. In Scala we represent them as any collection that implements Seq:

import java.util.Date

final case class Book(id: Int, notes: List[String], pages: Vector[Int], history: Seq[Date])

ctx.run(query[Book])
// SELECT x.id, x.notes, x.pages, x.history FROM Book x

Note that not all drivers/databases provides such feature hence only PostgresJdbcContext support SQL Arrays.

Cassandra-specific encoding

val ctx = new CassandraMirrorContext(Literal)
import ctx._

Collections

The Cassandra context provides List, Set, and Map encoding:


final case class Book(id: Int, notes: Set[String], pages: List[Int], history: Map[Int, Boolean])

ctx.run(query[Book])
// SELECT id, notes, pages, history FROM Book

User-Defined Types

The cassandra context provides encoding of UDT (user-defined types).


final case class Name(firstName: String, lastName: String) extends Udt

To encode the UDT and bind it into the query (insert/update queries), the context needs to retrieve UDT metadata from the cluster object. By default, the context looks for UDT metadata within the currently logged keyspace, but it's also possible to specify a concrete keyspace with udtMeta:

implicit val nameMeta = udtMeta[Name]("keyspace2.my_name")

When a keyspace is not set in udtMeta then the currently logged one is used.

Since it's possible to create a context without specifying a keyspace, (e.g. the keyspace parameter is null and the session is not bound to any keyspace), the UDT metadata will be resolved throughout the entire cluster.

It is also possible to rename UDT columns with udtMeta:

implicit val nameMeta = udtMeta[Name]("name", _.firstName -> "first", _.lastName -> "last")

Cassandra-specific operations

The cassandra context also provides a few additional operations:

allowFiltering

val q = quote {
query[Person].filter(p => p.age > 10).allowFiltering
}
ctx.run(q)
// SELECT id, name, age FROM Person WHERE age > 10 ALLOW FILTERING

ifNotExists

val q = quote {
query[Person].insert(_.age -> 10, _.name -> "John").ifNotExists
}
ctx.run(q)
// INSERT INTO Person (age,name) VALUES (10, 'John') IF NOT EXISTS

ifExists

val q = quote {
query[Person].filter(p => p.name == "John").delete.ifExists
}
ctx.run(q)
// DELETE FROM Person WHERE name = 'John' IF EXISTS

usingTimestamp

val q1 = quote {
query[Person].insert(_.age -> 10, _.name -> "John").usingTimestamp(99)
}
ctx.run(q1)
// INSERT INTO Person (age,name) VALUES (10, 'John') USING TIMESTAMP 99

val q2 = quote {
query[Person].usingTimestamp(99).update(_.age -> 10)
}
ctx.run(q2)
// UPDATE Person USING TIMESTAMP 99 SET age = 10

usingTtl

val q1 = quote {
query[Person].insert(_.age -> 10, _.name -> "John").usingTtl(11)
}
ctx.run(q1)
// INSERT INTO Person (age,name) VALUES (10, 'John') USING TTL 11

val q2 = quote {
query[Person].usingTtl(11).update(_.age -> 10)
}
ctx.run(q2)
// UPDATE Person USING TTL 11 SET age = 10

val q3 = quote {
query[Person].usingTtl(11).filter(_.name == "John").delete
}
ctx.run(q3)
// DELETE FROM Person USING TTL 11 WHERE name = 'John'

using

val q1 = quote {
query[Person].insert(_.age -> 10, _.name -> "John").using(ts = 99, ttl = 11)
}
ctx.run(q1)
// INSERT INTO Person (age,name) VALUES (10, 'John') USING TIMESTAMP 99 AND TTL 11

val q2 = quote {
query[Person].using(ts = 99, ttl = 11).update(_.age -> 10)
}
ctx.run(q2)
// UPDATE Person USING TIMESTAMP 99 AND TTL 11 SET age = 10

val q3 = quote {
query[Person].using(ts = 99, ttl = 11).filter(_.name == "John").delete
}
ctx.run(q3)
// DELETE FROM Person USING TIMESTAMP 99 AND TTL 11 WHERE name = 'John'

ifCond

val q1 = quote {
query[Person].update(_.age -> 10).ifCond(_.name == "John")
}
ctx.run(q1)
// UPDATE Person SET age = 10 IF name = 'John'

val q2 = quote {
query[Person].filter(_.name == "John").delete.ifCond(_.age == 10)
}
ctx.run(q2)
// DELETE FROM Person WHERE name = 'John' IF age = 10

delete column

val q = quote {
query[Person].map(p => p.age).delete
}
ctx.run(q)
// DELETE p.age FROM Person

list.contains / set.contains

requires allowFiltering

val q = quote {
query[Book].filter(p => p.pages.contains(25)).allowFiltering
}
ctx.run(q)
// SELECT id, notes, pages, history FROM Book WHERE pages CONTAINS 25 ALLOW FILTERING

map.contains

requires allowFiltering

val q = quote {
query[Book].filter(p => p.history.contains(12)).allowFiltering
}
ctx.run(q)
// SELECT id, notes, pages, history FROM book WHERE history CONTAINS 12 ALLOW FILTERING

map.containsValue

requires allowFiltering

val q = quote {
query[Book].filter(p => p.history.containsValue(true)).allowFiltering
}
ctx.run(q)
// SELECT id, notes, pages, history FROM book WHERE history CONTAINS true ALLOW FILTERING

Dynamic queries

Quill's default operation mode is compile-time, but there are queries that have their structure defined only at runtime. Quill automatically falls back to runtime normalization and query generation if the query's structure is not static. Example:

val ctx = new SqlMirrorContext(MirrorSqlDialect, Literal)

import ctx._

sealed trait QueryType
case object Minor extends QueryType
case object Senior extends QueryType

def people(t: QueryType): Quoted[Query[Person]] =
t match {
case Minor => quote {
query[Person].filter(p => p.age < 18)
}
case Senior => quote {
query[Person].filter(p => p.age > 65)
}
}

ctx.run(people(Minor))
// SELECT p.id, p.name, p.age FROM Person p WHERE p.age < 18

ctx.run(people(Senior))
// SELECT p.id, p.name, p.age FROM Person p WHERE p.age > 65

Dynamic query API

Additionally, Quill provides a separate query API to facilitate the creation of dynamic queries. This API allows users to easily manipulate quoted values instead of working only with quoted transformations.

Important: A few of the dynamic query methods accept runtime string values. It's important to keep in mind that these methods could be a vector for SQL injection.

Let's use the filter transformation as an example. In the regular API, this method has no implementation since it's an abstract member of a trait:

def filter(f: T => Boolean): EntityQuery[T]

In the dynamic API, filter is has a different signature and a body that is executed at runtime:

def filter(f: Quoted[T] => Quoted[Boolean]): DynamicQuery[T] =
transform(f, Filter)

It takes a Quoted[T] as input and produces a Quoted[Boolean]. The user is free to use regular scala code within the transformation:

def people(onlyMinors: Boolean) =
dynamicQuery[Person].filter(p => if(onlyMinors) quote(p.age < 18) else quote(true))

In order to create a dynamic query, use one of the following methods:

dynamicQuery[Person]
dynamicQuerySchema[Person]("people", alias(_.name, "pname"))

It's also possible to transform a Quoted into a dynamic query:

val q = quote {
query[Person]
}
q.dynamic.filter(p => quote(p.name == "John"))

The dynamic query API is very similar to the regular API but has a few differences:

Queries

// schema queries use `alias` instead of tuples
dynamicQuerySchema[Person]("people", alias(_.name, "pname"))

// this allows users to use a dynamic list of aliases
val aliases = List(alias[Person](_.name, "pname"), alias[Person](_.age, "page"))
dynamicQuerySchema[Person]("people", aliases:_*)

// a few methods have an overload with the `Opt` suffix,
// which apply the transformation only if the option is defined:

def people(minAge: Option[Int]) =
dynamicQuery[Person].filterOpt(minAge)((person, minAge) => quote(person.age >= minAge))

def people(maxRecords: Option[Int]) =
dynamicQuery[Person].takeOpt(maxRecords)

def people(dropFirst: Option[Int]) =
dynamicQuery[Person].dropOpt(dropFirst)

// method with `If` suffix, for better chaining
def people(userIds: Seq[Int]) =
dynamicQuery[Person].filterIf(userIds.nonEmpty)(person => quote(liftQuery(userIds).contains(person.id)))

Actions

// actions use `set`
dynamicQuery[Person].filter(_.id == 1).update(set(_.name, quote("John")))

// or `setValue` if the value is not quoted
dynamicQuery[Person].insert(setValue(_.name, "John"))

// or `setOpt` that will be applied only the option is defined
dynamicQuery[Person].insert(setOpt(_.name, Some("John")))

// it's also possible to use a runtime string value as the column name
dynamicQuery[Person].filter(_.id == 1).update(set("name", quote("John")))

// to insert or update a case class instance, use `insertValue`/`updateValue`
val p = Person(0, "John", 21)
dynamicQuery[Person].insertValue(p)
dynamicQuery[Person].filter(_.id == 1).updateValue(p)

Dynamic query normalization cache

Quill is super fast for static queries (almost zero runtime overhead compared to directly sql executing).

But there is significant impact for dynamic queries.

Normalization caching was introduced to improve the situation, which will speedup dynamic queries significantly. It is enabled by default.

To disable dynamic normalization caching, pass following property to sbt during compile time

sbt -Dquill.query.cacheDynamic=false