unique constraint for user and role

Author: stevethomas

database/migrations/2020_03_16_055658_create_roles_table.php

@@ -19,6 +19,8 @@ public function up()
             $table->integer('role_id')->unsigned();
             $table->integer('user_id')->unsigned();
             $table->timestamps();
+
+            $table->unique(['user_id', 'role_id']);
         });
     }