我試圖在 laraval 5.8 中使用 php artisan migrate 命令更改我的 char 類型列默認值，但出現以下錯誤：Unknown column type "char" requested. Any Doctrine type that you use has to be registered with \Doctrine\DBAL\Types\Type::addType(). You can get a list of all the known types with \Doctrine\DBAL\Types\Type::getTypesMap(). If this error occurs during database introspection then you might have forgotten to register all database types for a Doctrine Type. Use AbstractPlatform#registerDoctrineTypeMapping() or have your custom types implement Type#getMappedDatabaseTypes(). If the type name is empty you might have a problem with the cache or forgot some mapping information.我當前的腳本如下：use Illuminate\Support\Facades\Schema;use Illuminate\Database\Schema\Blueprint;use Illuminate\Database\Migrations\Migration;class AddTypeDeafultValueProjectsTable extends Migration{/** * Run the migrations. * * @return void */public function up(){    Schema::table('projects', function (Blueprint $table) {        $table->char('type', 50)->nullable(true)->change();    });}/** * Reverse the migrations. * * @return void */public function down(){    Schema::table('projects', function (Blueprint $table) {        //    });}}我沒有遇到其他數據類型列的問題，但僅針對 char 出現上述錯誤?？梢詭臀医鉀Q這個問題嗎？