November 16, 2021 in Laravel, Tips and Tricks
Joins in Laravel
The query builder may also be used to add join clauses to your queries. To perform a basic “inner join”, you may use the join method on a query builder instance. The first argument passed to the join method is the name of the table you need to join to, while the remaining arguments specify the column constraints for the join. You may even join multiple tables in a single query:
use Illuminate\Support\Facades\DB;
$users = DB::table('users')
->join('contacts', 'users.id', '=', 'contacts.user_id')
->join('orders', 'users.id', '=', 'orders.user_id')
->select('users.*', 'contacts.phone', 'orders.price')
->get();
If you would like to perform a “left join” or “right join” instead of an “inner join”, use the leftJoin or rightJoin methods. These methods have the same signature as the join method:
$users = DB::table('users')
->leftJoin('posts', 'users.id', '=', 'posts.user_id')
->get();
$users = DB::table('users')
->rightJoin('posts', 'users.id', '=', 'posts.user_id')
->get();
You may use the crossJoin method to perform a “cross join”. Cross joins generate a cartesian product between the first table and the joined table:
$sizes = DB::table('sizes')
->crossJoin('colors')
->get();
You may also specify more advanced join clauses. To get started, pass a closure as the second argument to the join method. The closure will receive a Illuminate\Database\Query\JoinClause instance which allows you to specify constraints on the “join” clause:
DB::table('users')
->join('contacts', function ($join) {
$join->on('users.id', '=', 'contacts.user_id')->orOn(...);
})
->get();
If you would like to use a “where” clause on your joins, you may use the where and orWhere methods provided by the JoinClause instance. Instead of comparing two columns, these methods will compare the column against a value:
DB::table('users')
->join('contacts', function ($join) {
$join->on('users.id', '=', 'contacts.user_id')
->where('contacts.user_id', '>', 5);
})
->get();
You may use the joinSub, leftJoinSub, and rightJoinSub methods to join a query to a subquery. Each of these methods receives three arguments: the subquery, its table alias, and a closure that defines the related columns. In this example, we will retrieve a collection of users where each user record also contains the created_at timestamp of the user’s most recently published blog post:
$latestPosts = DB::table('posts')
->select('user_id', DB::raw('MAX(created_at) as last_post_created_at'))
->where('is_published', true)
->groupBy('user_id');
$users = DB::table('users')
->joinSub($latestPosts, 'latest_posts', function ($join) {
$join->on('users.id', '=', 'latest_posts.user_id');
})->get();
