How to get distinct values for non-key column fields in Laravel?

In Laravel, you can retrieve distinct values for non-key column fields using several methods. Let's explore different approaches to get unique values from a database table.

Assume we have a students table created with the following structure ?

CREATE TABLE students( 
   id          INTEGER        NOT NULL      PRIMARY KEY, 
   name        VARCHAR(15)    NOT NULL, 
   email       VARCHAR(20)    NOT NULL, 
   created_at  VARCHAR(27), 
   updated_at  VARCHAR(27), 
   address     VARCHAR(30)    NOT NULL 
);

Sample data in the table ?

+----+---------------+------------------+-----------------------------+-----------------------------+---------+ 
| id |          name |            email |           created_at        |       updated_at            | address | 
+----+---------------+------------------+-----------------------------+-----------------------------+---------+ 
| 1  | Siya  Khan    | siya@gmail.com   | 2022-05-01T13:45:55.000000Z | 2022-05-01T13:45:55.000000Z | Xyz     | 
| 2  | Rehan Khan    | rehan@gmail.com  | 2022-05-01T13:49:50.000000Z | 2022-05-01T13:49:50.000000Z | Xyz     | 
| 3  | Rehan Khan    | rehan@gmail.com  |           NULL              | NULL                        | testing | 
| 4  | Rehan         | rehan@gmail.com  |           NULL              | NULL                        | abcd    |
+----+---------------+------------------+-----------------------------+-----------------------------+---------+

Using Eloquent distinct() Method

The distinct() method returns unique values from a specified column using Eloquent ORM ?

<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Models\Student;

class StudentController extends Controller {
   public function index() {
      $student = Student::select('name')->distinct()->get()->toArray();
       print_r($student);
   }
}
?>

The output of the above code is ?

Array(
   [0] => Array(
      [name] => Siya Khan
   )
   [1] => Array(
      [name] => Rehan Khan
   )
   [2] => Array(
      [name] => Rehan
   )
)

Using groupBy() Method

The groupBy() method groups records by a specific field, effectively providing distinct values ?

<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Models\Student;

class StudentController extends Controller {
   public function index() {
      $student = Student::select('name')->groupBy('name')->get()->toArray();
      print_r($student);
   }
}
?>

The output of the above code is ?

Array ( 
   [0] => Array ( 
      [name] => Rehan 
   )
   [1] => Array ( 
      [name] => Rehan Khan 
   )
   [2] => Array ( 
      [name] => Siya Khan 
   )
)

Using unique() Method on Collections

The unique() method filters unique values from a Laravel collection after retrieving all records ?

<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Models\Student;

class StudentController extends Controller {
   public function index() {
      $student = Student::all()->unique('name')->toArray();
      print_r($student);
   }
}
?>

The output of the above code shows complete records for unique names ?

Array(
   [0] => Array(
      [id] => 1
      [name] => Siya Khan
      [email] => siya@gmail.com
      [created_at] => 2022-05-01T13:45:55.000000Z
      [updated_at] => 2022-05-01T13:45:55.000000Z
      [address] => Xyz
   )
   [1] => Array(
      [id] => 2
      [name] => Rehan Khan
      [email] => rehan@gmail.com
      [created_at] => 2022-05-01T13:49:50.000000Z
      [updated_at] => 2022-05-01T13:49:50.000000Z
      [address] => Xyz
   )
   [3] => Array(
      [id] => 4
      [name] => Rehan
      [email] => rehan@gmail.com
      [created_at] => 
      [updated_at] => 
      [address] => abcd
   )
)

Using DB Facade with distinct()

You can also use Laravel's DB facade to get distinct values ?

<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use DB;

class StudentController extends Controller{
   public function index() {
      $stdDetails = DB::table('students')->distinct()->get(['name'])->toArray();
      print_r($stdDetails);
   }
}
?>

The output of the above code is ?

Array ( 
   [0] => stdClass Object ( 
      [name] => Siya Khan 
   )
   [1] => stdClass Object( 
      [name] => Rehan Khan 
   )
   [2] => stdClass Object ( 
      [name] => Rehan 
   )
)

Using pluck() with groupBy()

For a simpler array output, combine groupBy() with pluck() ?

<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use DB;

class StudentController extends Controller{
   public function index() {
      $stdDetails = DB::table('students')->select('name')->groupBy('name')->get()->pluck('name')->all();
      print_r($stdDetails);
   }
}
?>

The output of the above code is ?

Array(
   [0] => Rehan
   [1] => Rehan Khan
   [2] => Siya Khan
)

Conclusion

Use distinct() or groupBy() for database-level filtering, and unique() for collection-level filtering. The pluck() method provides clean array output when you only need the values.