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Complex selections

You can select arbitrary expression including subqueries and raw sql snippets. When you do that, you need to give a name for the selections using the as method:

import type {
ColumnType,
Generated,
GeneratedAlways,
Insertable,
Kysely,
Selectable,
SqlBool,
Updateable,
} from 'kysely'

export interface Database {
audit: AuditTable
person: PersonTable
person_backup: PersonTable
pet: PetTable
toy: ToyTable
wine: WineTable
wine_stock_change: WineStockChangeTable
}

interface AuditTable {
id: Generated<number>
action: string
}

interface PersonTable {
id: Generated<number>
address: { city: string } | null
age: number | null
birthdate: ColumnType<Date | null, string | null | undefined, string | null>
created_at: GeneratedAlways<Date>
deleted_at: ColumnType<Date | null, string | null | undefined, string | null>
experience: { role: string }[] | null
first_name: string
gender: 'male' | 'female' | 'other' | null
has_pets: Generated<'Y' | 'N'>
last_name: string | null
middle_name: string | null
nicknames: string[] | null
nullable_column: string | null
profile: {
addresses: { city: string }[]
website: { url: string }
} | null
updated_at: ColumnType<Date | null, string | null | undefined, string | null>
marital_status: 'single' | 'married' | 'divorced' | 'widowed' | null
}

interface PetTable {
id: Generated<number>
created_at: GeneratedAlways<Date>
is_favorite: Generated<SqlBool>
name: string
owner_id: number
species: Species
}

interface ToyTable {
id: Generated<number>
name: string
pet_id: number
price: number
}

interface WineTable {
id: Generated<number>
name: string
stock: number
}

interface WineStockChangeTable {
id: Generated<number>
stock_delta: number
wine_name: string
}

export type Person = Selectable<PersonTable>
export type NewPerson = Insertable<PersonTable>
export type PersonUpdate = Updateable<PersonTable>
export type Pet = Selectable<PetTable>
export type NewPet = Insertable<PetTable>
export type PetUpdate = Updateable<PetTable>
export type Species = 'dog' | 'cat' | 'hamster'

declare global {
// @ts-ignore
export class Buffer {
static isBuffer(obj: unknown): obj is { length: number }
static compare(a: Buffer, b: Buffer): number
}
export const db: Kysely<Database>
export function functionThatExpectsPersonWithNonNullValue(
person: Person & { nullable_column: string },
): void
}


import { sql } from 'kysely'

const persons = await db.selectFrom('person')
.select(({ eb, selectFrom, or, val, lit }) => [
// Select a correlated subquery
selectFrom('pet')
.whereRef('person.id', '=', 'pet.owner_id')
.select('pet.name')
.orderBy('pet.name')
.limit(1)
.as('first_pet_name'),

// Build and select an expression using
// the expression builder
or([
eb('first_name', '=', 'Jennifer'),
eb('first_name', '=', 'Arnold')
]).as('is_jennifer_or_arnold'),

// Select a raw sql expression
sql<string>`concat(first_name, ' ', last_name)`.as('full_name'),

// Select a static string value
val('Some value').as('string_value'),

// Select a literal value
lit(42).as('literal_value'),
])
.execute()
More examples

The API documentation is packed with examples. The API docs are hosted here, but you can access the same documentation by hovering over functions/methods/classes in your IDE. The examples are always just one hover away!

For example, check out these sections: