Joins another table to the query using an inner join.

Examples

Simple usage by providing a table name and two columns to join:

const result = await db
  .selectFrom('person')
  .innerJoin('pet', 'pet.owner_id', 'person.id')
  // `select` needs to come after the call to `innerJoin` so
  // that you can select from the joined table.
  .select(['person.id', 'pet.name'])
  .execute()

result[0].id
result[0].name

The generated SQL (PostgreSQL):

select "person"."id", "pet"."name"
from "person"
inner join "pet"
on "pet"."owner_id" = "person"."id"

You can give an alias for the joined table like this:

await db.selectFrom('person')
  .innerJoin('pet as p', 'p.owner_id', 'person.id')
  .where('p.name', '=', 'Doggo')
  .selectAll()
  .execute()

The generated SQL (PostgreSQL):

select *
from "person"
inner join "pet" as "p"
on "p"."owner_id" = "person"."id"
where "p".name" = $1

You can provide a function as the second argument to get a join builder for creating more complex joins. The join builder has a bunch of on* methods for building the on clause of the join. There's basically an equivalent for every where method (on, onRef, onExists etc.). You can do all the same things with the on method that you can with the corresponding where method. See the where method documentation for more examples.

await db.selectFrom('person')
  .innerJoin(
    'pet',
    (join) => join
      .onRef('pet.owner_id', '=', 'person.id')
      .on('pet.name', '=', 'Doggo')
  )
  .selectAll()
  .execute()

The generated SQL (PostgreSQL):

select *
from "person"
inner join "pet"
on "pet"."owner_id" = "person"."id"
and "pet"."name" = $1

You can join a subquery by providing a select query (or a callback) as the first argument:

await db.selectFrom('person')
  .innerJoin(
    qb.selectFrom('pet')
      .select(['owner_id', 'name'])
      .where('name', '=', 'Doggo')
      .as('doggos'),
    'doggos.owner_id',
    'person.id',
  )
  .selectAll()
  .execute()

The generated SQL (PostgreSQL):

select *
from "person"
inner join (
  select "owner_id", "name"
  from "pet"
  where "name" = $1
) as "doggos"
on "doggos"."owner_id" = "person"."id"