SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 1000 bytes

Laravel5.4默认使用utf8mb4字符编码，而不是之前的utf8编码。因此运行php artisan migrate 会出现如下错误：

Illuminate\Database\QueryException
SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 1000 bytes

原因：mysql版本较低

解决办法：

app\Providers\AppServiceProvider.php下boot()方法添加：

Schema::defaultStringLength(191);