Joins

Last updated 4 years ago

Join clauses range from simple to complex including joining complete subqueries on multiple conditions. qb has your back with all of these use cases.

join

Applies a join to the query. The simplest join is to a table based on two columns:

QueryBuilder

query.from( "users" )
    .join( "posts", "users.id", "=", "posts.author_id" );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`

When doing a simple join using = as the operator, you can omit it and pass just the column names:

QueryBuilder

query.from( "users" )
    .join( "posts", "users.id", "posts.author_id" );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`

``Expressions are also supported as the table argument (though you may prefer the readability of the joinRaw method):

QueryBuilder

query.from( "users" )
    .join( query.raw( "posts (nolock)" ), "users.id", "=", "posts.author_id" );

SQL Server

SELECT *
FROM [users]
JOIN posts (nolock)
  ON [users].[id] = [posts].[author_id]

Using raw will most likely tie your code to a specific database, so think carefully before using the raw method if you want your project to be database agnostic.

When you need to specify more clauses to join, you can pass a function as the second argument:

QueryBuilder

query.from( "users" )
    .join( "posts", function( j ) {
        j.on( "users.id", "=", "posts.author_id" );
        j.on( "users.prefix", "=", "posts.prefix" );
    } );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`
  AND `users`.`prefix` = `posts`.`prefix`

You can specify where clauses in your joins as well.

QueryBuilder

query.from( "users" )
    .join( "posts", function( j ) {
        j.on( "users.id", "=", "posts.author_id" );
        j.whereNotNull( "posts.published_date" );
    } );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`
  AND `posts`.`published_date` IS NOT NULL

Conditions inside a join clause can be grouped using a function.

QueryBuilder

query.from( "users" )
    .join( "posts", function( j ) {
        j.on( function( j1 ) {
            j1.on( "users.id", "posts.author_id" )
                .orOn( "users.id", "posts.reviewer_id" );
        } );
        j.whereNotNull( "posts.published_date" );
    } );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON (
      `users`.`id` = `posts`.`author_id`
      OR `users`.`id` = `posts`.`reviewer_id`
  )
  AND `posts`.`published_date` IS NOT NULL

A preconfigured JoinClause can also be passed to the join function. This allows you to extract shared pieces of code out to different functions.

QueryBuilder

var j = query.newJoin( "contacts" )
    .on( "users.id", "posts.author_id" );

query.from( "users" ).join( j );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`

joinWhere

Adds a join to another table based on a WHERE clause instead of an ON clause. WHERE clauses introduce parameters and parameter bindings whereas on clauses join between columns and don't need parameter bindings.

For simple joins, this specifies a column on which to join the two tables:

QueryBuilder

query.from( "users" )
    .joinWhere( "contacts", "contacts.balance", "<", 100 );

MySQL

SELECT *
FROM `users`
JOIN `contacts`
  WHERE `contacts`.`balance` < ?

For complex joins, a function can be passed to first. This allows multiple on and where conditions to be applied to the join. See the documentation for join for more information.

joinRaw

Uses the raw SQL provided to as the table for the join clause. All the other functionality of joinRaw matches the join method. Additionally, there are leftJoinRaw, rightJoinRaw, and crossJoinRaw methods available.

QueryBuilder

query.from( "users" )
    .joinRaw( "posts (nolock)", "users.id", "posts.author_id" );

SQL Server

SELECT *
FROM [users]
JOIN posts (nolock)
  ON [users].[id] = [posts].[author_id]

Using joinRaw will most likely tie your code to a specific database, so think carefully before using the joinRaw method if you want your project to be database agnostic.

joinSub

Adds a join to a derived table. All the functionality of the join method applies to constrain the query. The derived table can be defined using a QueryBuilder instance:

QueryBuilder

var sub = query.newQuery()
    .select( "id" )
    .from( "contacts" )
    .whereNotIn( "id", [ 1, 2, 3 ] );

query.from( "users as u" )
    .joinSub( "c", sub, "u.id", "=", "c.id" );

MySQL

SELECT *
FROM `users` AS `u`
JOIN (
  SELECT `id`
  FROM `contacts`
  WHERE `id` NOT IN (?, ?, ?)
) AS `c`
  ON `u`.`id` = `c`.`id`

Alternatively, a function may be used to define the derived table:

QueryBuilder

query.from( "users as u" )
    .joinSub( "c", function ( q ) {
        q.select( "id" )
            .from( "contacts" )
            .whereNotIn( "id", [ 1, 2, 3 ] );
    }, "u.id", "=", "c.id" );

MySQL

SELECT *
FROM `users` AS `u`
JOIN (
  SELECT `id`
  FROM `contacts`
  WHERE `id` NOT IN (?, ?, ?)
) AS `c`
  ON `u`.`id` = `c`.`id`

Complex join conditions are also possible by passing a function as the third parameter:

QueryBuilder

query.from( "users as u" )
    .joinSub( "c", function ( q ) {
        q.select( "id" )
            .from( "contacts" )
            .whereNotIn( "id", [ 1, 2, 3 ] );
    }, function( j ) {
        j.on( "u.id", "c.id" );
        j.on( "u.type", "c.type" );
    } );

MySQL

SELECT *
FROM `users` AS `u`
JOIN (
  SELECT `id`
  FROM `contacts`
  WHERE `id` NOT IN (?, ?, ?)
) AS `c`
  ON `u`.`id` = `c`.`id`
  AND `u`.`type` = `c`.`type`

leftJoin

QueryBuilder

query.from( "posts" )
    .leftJoin( "users", "users.id", "posts.author_id" );

MySQL

SELECT *
FROM `posts`
LEFT JOIN `users`
  ON `users`.`id` = `posts`.`author_id`

leftJoinRaw

Uses the raw SQL provided to as the table for the left join clause. All the other functionality of leftJoinRaw matches the join method.

QueryBuilder

query.from( "posts" )
    .leftJoinRaw( "users (nolock)", "users.id", "posts.author_id" );

SQL Server

SELECT *
FROM [posts]
LEFT JOIN users (nolock)
  ON [users].[id] = [posts].[author_id]

Using leftJoinRaw will most likely tie your code to a specific database, so think carefully before using the leftJoinRaw method if you want your project to be database agnostic.

leftJoinSub

Adds a left join to a derived table. All the functionality of the joinSub method applies to define and constrain the query.

QueryBuilder

var sub = query.newQuery()
    .select( "id" )
    .from( "contacts" )
    .whereNotIn( "id", [ 1, 2, 3 ] );

query.from( "users as u" )
    .leftJoinSub( "c", sub, "u.id", "=", "c.id" );

MySQL

SELECT *
FROM `users` AS `u`
LEFT JOIN (
  SELECT `id`
  FROM `contacts`
  WHERE `id` NOT IN (?, ?, ?)
) AS `c`
  ON `u`.`id` = `c`.`id`

rightJoin

QueryBuilder

query.from( "users" )
    .rightJoin( "posts", "users.id", "posts.author_id" );

MySQL

SELECT *
FROM `users`
RIGHT JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`

rightJoinRaw

Uses the raw SQL provided to as the table for the right join clause. All the other functionality of rightJoinRaw matches the join method.

QueryBuilder

query.from( "users" )
    .rightJoinRaw( "posts (nolock)", "users.id", "posts.author_id" );

SQL Server

SELECT *
FROM [users]
LEFT JOIN posts (nolock)
  ON [users].[id] = [posts].[author_id]

Using rightJoinRaw will most likely tie your code to a specific database, so think carefully before using the rightJoinRaw method if you want your project to be database agnostic.

rightJoinSub

Adds a right join to a derived table. All the functionality of the joinSub method applies to define and constrain the query.

QueryBuilder

var sub = query.newQuery()
    .select( "id" )
    .from( "contacts" )
    .whereNotIn( "id", [ 1, 2, 3 ] );

query.from( "users as u" )
    .rightJoinSub( "c", sub, "u.id", "=", "c.id" );

MySQL

SELECT *
FROM `users` AS `u`
RIGHT JOIN (
  SELECT `id`
  FROM `contacts`
  WHERE `id` NOT IN (?, ?, ?)
) AS `c`
  ON `u`.`id` = `c`.`id`

crossJoin

QueryBuilder

query.from( "users" ).crossJoin( "posts" );

MySQL

SELECT *
FROM `users`
CROSS JOIN `posts`

crossJoinRaw

Uses the raw SQL provided to as the table for the cross join clause. Cross joins cannot be further constrained with on or where clauses.

QueryBuilder

query.from( "users" ).crossJoinRaw( "posts (nolock)" );

SQL Server

SELECT *
FROM [users]
CROSS JOIN posts (nolock)

Using crossJoinRaw will most likely tie your code to a specific database, so think carefully before using the crossJoinRaw method if you want your project to be database agnostic.

crossJoinSub

Adds a cross join to a derived table. The derived table can be defined using a QueryBuilder instance or a function just as with joinSub. Cross joins cannot be constrained, however.

QueryBuilder

var sub = query.newQuery()
    .select( "id" )
    .from( "contacts" )
    .whereNotIn( "id", [ 1, 2, 3 ] );

query.from( "users as u" ).crossJoinSub( "c", sub );

MySQL

SELECT *
FROM `users` AS `u`
CROSS JOIN (
  SELECT `id`
  FROM `contacts`
  WHERE `id` NOT IN (?, ?, ?)
)

newJoin

Creates a new JoinClause. A JoinClause is a specialized version of a QueryBuilder. You may call on or orOn to constrain the JoinClause. You may also call any where methods.

Creating a JoinClause directly is useful when you need to share a join between different queries. You can create and configure the JoinClause in a function and pass it to queries as needed.

QueryBuilder

var j = query.newJoin( "contacts" )
    .on( "users.id", "posts.author_id" );

query.from( "users" ).join( j );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`

Although a JoinClause can be passed to join, leftJoin, rightJoin, and crossJoin, the type of the JoinClause will override the type of the function.

QueryBuilder

// This is still an inner join because
// the JoinClause is an inner join
var j = query.newJoin( "contacts", "inner" )
    .on( "users.id", "posts.author_id" );

query.from( "users" ).leftJoin( j );

MySQL

-- This is still an inner join because
-- the JoinClause is an inner join
SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`

JoinClause

A JoinClause is a specialized version of a QueryBuilder. You may call on or orOn to constrain the JoinClause. You may also call any where methods.

on

Applies a join condition to the JoinClause. An alias for whereColumn.

QueryBuilder

var j = query.newJoin( "contacts" )
    .on( "users.id", "posts.author_id" );

query.from( "users" ).join( j );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`

orOn

Applies a join condition to the JoinClause using an or combinator. An alias for orWhereColumn.

QueryBuilder

var j = query.newJoin( "contacts" )
    .on( "users.id", "posts.author_id" )
    .orOn( "users.id", "posts.reviewer_id" );

query.from( "users" ).join( j );

MySQL

SELECT *
FROM `users`
JOIN `posts`
  ON `users`.`id` = `posts`.`author_id`
  OR `users`.`id` = `posts`.`reviewer_id`