如何在Laravel 5.6中计算表列的唯一值？

php artisan make:migration add_unique_constraint_to_table --table=your_table_name

public function up()
{
    Schema::table('your_table_name', function (Blueprint $table) {
        $table->string('email')->unique();
    });
}

php artisan migrate

public static $rules = [
    'email' => 'required|email|unique:users',
];