laravel 表遷移報錯

error infomation:

Illuminate\Database\QueryException  : SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes (SQL: alter table `use
rs` add unique `users_email_unique`(`email`))

  at D:\WWW\test\vendor\laravel\framework\src\Illuminate\Database\Connection.php:664
    660|         // If an exception occurs when attempting to run a query, we'll format the error
    661|         // message to include the bindings with SQL, which will make this exception a
    662|         // lot more helpful to the developer instead of just the database's errors.
    663|         catch (Exception $e) {
  > 664|             throw new QueryException(
    665|                 $query, $this->prepareBindings($bindings), $e
    666|             );
    667|         }
    668|

  Exception trace:

  1   PDOException::("SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes")
      D:\WWW\test\vendor\laravel\framework\src\Illuminate\Database\Connection.php:458

  2   PDOStatement::execute()
      D:\WWW\test\vendor\laravel\framework\src\Illuminate\Database\Connection.php:458

  Please use the argument -v to see more details.

解決：
索引長度 & Mysql / MariaDB
Laravel 默認使用 utf8mb4 編碼，它支持在數據庫中儲存 emojis 。如果你是在版本低於 5.7.7 的 MySQL 或者版本低於 10.2.2 的 MariaDB 上創建索引，那你就需要手動配置數據庫遷移的默認字符串長度。
即在 AppServiceProvider 中調用 Schema::defaultStringLength 方法來配置它：

use Illuminate\Support\Facades\Schema;

/**
 * 引導任何應用程序服務
 *
 * @return void
 */
 public function boot()
 {
     Schema::defaultStringLength(191);
 }