Last Updated: 3/9/2026

kysely

• ExpressionWrapper

Class ExpressionWrapper

An expression with an as method.

Type Parameters

• DB
• TB extends keyof DB
• T

Implements

• AliasableExpression<T>

Index

Constructors

Methods

$castTo $notNull and as or toOperationNode

Constructors

constructor

• new ExpressionWrapper<DB, TB extends string | number | symbol, T>(
      node: OperationNode,
  ): ExpressionWrapper<DB, TB, T>

  Type Parameters

  • DB
  • TB extends string | number | symbol
  • T

  Parameters

  • node: OperationNode

  Returns ExpressionWrapper<DB, TB, T>

Methods

$castTo

• $castTo<C>(): ExpressionWrapper<DB, TB, C>

  Change the output type of the expression.

  This method call doesn’t change the SQL in any way. This methods simply returns a copy of this ExpressionWrapper with a new output type.

  Type Parameters

  • C

  Returns ExpressionWrapper<DB, TB, C>

$notNull

• $notNull(): ExpressionWrapper<DB, TB, Exclude<T, null>>

  Omit null from the expression’s type.

  This function can be useful in cases where you know an expression can’t be null, but Kysely is unable to infer it.

  This method call doesn’t change the SQL in any way. This methods simply returns a copy of this with a new output type.

  Returns ExpressionWrapper<DB, TB, Exclude<T, null>>

and

• and<
      RE extends
          | string
          | Expression
          | DynamicReferenceBuilder
          | SelectQueryBuilderExpression<Record<string, any>>
          | OperandExpressionFactory<DB, TB, any>,
      VE extends any,

  (
      lhs: RE,
      op: ComparisonOperatorExpression,
      rhs: VE,
  ): T extends SqlBool
      ? AndWrapper<DB, TB, SqlBool>
      : KyselyTypeError<“and() method can only be called on boolean expressions”>

  Combines this and another expression using AND.

  Also see ExpressionBuilder.and

  Examples

  const  result = await  db. selectFrom('person') . selectAll() . where(eb  =>  eb('first_name', '=', 'Jennifer') . and('last_name', '=', 'Aniston') . and('age', '>', 40) ) . execute()

  The generated SQL (PostgreSQL):

  select * from "person" where ( "first_name" = $1 and "last_name" = $2 and "age" > $3 ) 

  You can also pass any expression as the only argument to this method:

  const  result = await  db. selectFrom('person') . selectAll() . where(eb  =>  eb('first_name', '=', 'Jennifer') . and(eb('first_name', '=', 'Sylvester'). or('last_name', '=', 'Stallone')) . and(eb. exists( eb. selectFrom('pet') . select('id') . whereRef('pet.owner_id', '=', 'person.id') )) ) . execute()

  The generated SQL (PostgreSQL):

  select * from "person" where ( "first_name" = $1 and ("first_name" = $2 or "last_name" = $3) and exists ( select "id" from "pet" where "pet"."owner_id" = "person"."id" ) ) 

  Type Parameters

  • RE extends
        | string
        | Expression
        | DynamicReferenceBuilder
        | SelectQueryBuilderExpression<Record<string, any>>
        | OperandExpressionFactory<DB, TB, any>
  • VE extends any

  Parameters

  • lhs: RE
  • op: ComparisonOperatorExpression
  • rhs: VE

  Returns T extends SqlBool     ? AndWrapper<DB, TB, SqlBool>     : KyselyTypeError<“and() method can only be called on boolean expressions”>

• and<E extends OperandExpression<SqlBool>>(
      expression: E,
  ): T extends SqlBool
      ? AndWrapper<DB, TB, SqlBool>
      : KyselyTypeError<“and() method can only be called on boolean expressions”>

  Combines this and another expression using AND.

  Also see ExpressionBuilder.and

  Examples

  const  result = await  db. selectFrom('person') . selectAll() . where(eb  =>  eb('first_name', '=', 'Jennifer') . and('last_name', '=', 'Aniston') . and('age', '>', 40) ) . execute()

  The generated SQL (PostgreSQL):

  select * from "person" where ( "first_name" = $1 and "last_name" = $2 and "age" > $3 ) 

  You can also pass any expression as the only argument to this method:

  const  result = await  db. selectFrom('person') . selectAll() . where(eb  =>  eb('first_name', '=', 'Jennifer') . and(eb('first_name', '=', 'Sylvester'). or('last_name', '=', 'Stallone')) . and(eb. exists( eb. selectFrom('pet') . select('id') . whereRef('pet.owner_id', '=', 'person.id') )) ) . execute()

  The generated SQL (PostgreSQL):

  select * from "person" where ( "first_name" = $1 and ("first_name" = $2 or "last_name" = $3) and exists ( select "id" from "pet" where "pet"."owner_id" = "person"."id" ) ) 

  Type Parameters

  • E extends OperandExpression<SqlBool>

  Parameters

  • expression: E

  Returns T extends SqlBool     ? AndWrapper<DB, TB, SqlBool>     : KyselyTypeError<“and() method can only be called on boolean expressions”>

as

• as<A extends string>(alias: A): AliasedExpression<T, A>

  Returns an aliased version of the expression.

  Examples

  In addition to slapping as "the_alias" to the end of the SQL, this method also provides strict typing:

  const  result = await  db . selectFrom('person') . select((eb) =>  eb('first_name', '=', 'Jennifer'). as('is_jennifer') ) . executeTakeFirstOrThrow()// `is_jennifer: SqlBool` field exists in the result type. console. log(result. is_jennifer)

  The generated SQL (PostgreSQL):

  select "first_name" = $1 as "is_jennifer" from "person" 

  Type Parameters

  • A extends string

  Parameters

  • alias: A

  Returns AliasedExpression<T, A>

• as<A extends string>(alias: Expression): AliasedExpression<T, A>

  Returns an aliased version of the expression.

  Examples

  In addition to slapping as "the_alias" to the end of the SQL, this method also provides strict typing:

  const  result = await  db . selectFrom('person') . select((eb) =>  eb('first_name', '=', 'Jennifer'). as('is_jennifer') ) . executeTakeFirstOrThrow()// `is_jennifer: SqlBool` field exists in the result type. console. log(result. is_jennifer)

  The generated SQL (PostgreSQL):

  select "first_name" = $1 as "is_jennifer" from "person" 

  Type Parameters

  • A extends string

  Parameters

  • alias: Expression

  Returns AliasedExpression<T, A>

or

• or<
      RE extends
          | string
          | Expression
          | DynamicReferenceBuilder
          | SelectQueryBuilderExpression<Record<string, any>>
          | OperandExpressionFactory<DB, TB, any>,
      VE extends any,

  (
      lhs: RE,
      op: ComparisonOperatorExpression,
      rhs: VE,
  ): T extends SqlBool
      ? OrWrapper<DB, TB, SqlBool>
      : KyselyTypeError<“or() method can only be called on boolean expressions”>

  Combines this and another expression using OR.

  Also see ExpressionBuilder.or

  Examples

  const  result = await  db. selectFrom('person') . selectAll() . where(eb  =>  eb('first_name', '=', 'Jennifer') . or('first_name', '=', 'Arnold') . or('first_name', '=', 'Sylvester') ) . execute()

  The generated SQL (PostgreSQL):

  select * from "person" where ( "first_name" = $1 or "first_name" = $2 or "first_name" = $3 ) 

  You can also pass any expression as the only argument to this method:

  const  result = await  db. selectFrom('person') . selectAll() . where(eb  =>  eb('first_name', '=', 'Jennifer') . or(eb('first_name', '=', 'Sylvester'). and('last_name', '=', 'Stallone')) . or(eb. exists( eb. selectFrom('pet') . select('id') . whereRef('pet.owner_id', '=', 'person.id') )) ) . execute()

  The generated SQL (PostgreSQL):

  select * from "person" where ( "first_name" = $1 or ("first_name" = $2 and "last_name" = $3) or exists ( select "id" from "pet" where "pet"."owner_id" = "person"."id" ) ) 

  Type Parameters

  • RE extends
        | string
        | Expression
        | DynamicReferenceBuilder
        | SelectQueryBuilderExpression<Record<string, any>>
        | OperandExpressionFactory<DB, TB, any>
  • VE extends any

  Parameters

  • lhs: RE
  • op: ComparisonOperatorExpression
  • rhs: VE

  Returns T extends SqlBool     ? OrWrapper<DB, TB, SqlBool>     : KyselyTypeError<“or() method can only be called on boolean expressions”>

• or<E extends OperandExpression<SqlBool>>(
      expression: E,
  ): T extends SqlBool
      ? OrWrapper<DB, TB, SqlBool>
      : KyselyTypeError<“or() method can only be called on boolean expressions”>

  Combines this and another expression using OR.

  Also see ExpressionBuilder.or

  Examples

  const  result = await  db. selectFrom('person') . selectAll() . where(eb  =>  eb('first_name', '=', 'Jennifer') . or('first_name', '=', 'Arnold') . or('first_name', '=', 'Sylvester') ) . execute()

  The generated SQL (PostgreSQL):

  select * from "person" where ( "first_name" = $1 or "first_name" = $2 or "first_name" = $3 ) 

  You can also pass any expression as the only argument to this method:

  const  result = await  db. selectFrom('person') . selectAll() . where(eb  =>  eb('first_name', '=', 'Jennifer') . or(eb('first_name', '=', 'Sylvester'). and('last_name', '=', 'Stallone')) . or(eb. exists( eb. selectFrom('pet') . select('id') . whereRef('pet.owner_id', '=', 'person.id') )) ) . execute()

  The generated SQL (PostgreSQL):

  select * from "person" where ( "first_name" = $1 or ("first_name" = $2 and "last_name" = $3) or exists ( select "id" from "pet" where "pet"."owner_id" = "person"."id" ) ) 

  Type Parameters

  • E extends OperandExpression<SqlBool>

  Parameters

  • expression: E

  Returns T extends SqlBool     ? OrWrapper<DB, TB, SqlBool>     : KyselyTypeError<“or() method can only be called on boolean expressions”>

toOperationNode

• toOperationNode(): OperationNode

  Creates the OperationNode that describes how to compile this expression into SQL.

  Examples

  If you are creating a custom expression, it’s often easiest to use the sql template tag to build the node:

  import { type  Expression, type  OperationNode, sql } from  'kysely' class  SomeExpression< T> implements  Expression< T> { get  expressionType(): T  | undefined { return  undefined }  toOperationNode(): OperationNode { return  sql `some sql here`. toOperationNode() }}

  Returns OperationNode

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$castTo$notNulland

• • • Examples
    • Examples

as

• • • Examples
    • Examples

or

• • • Examples
    • Examples

toOperationNode

• Examples