我正在尝试运行迁移(见下文)并为数据库播种,但是当我运行时
PHP artisan migrate --seed
我收到此错误:
Migration table created successfully.
Migrated: 2015_06_17_100000_create_users_table
Migrated: 2015_06_17_200000_create_password_resets_table
Migrated: 2015_06_17_300000_create_vehicles_table
[Illuminate\Database\QueryException]
sqlSTATE[42000]: Syntax error or access violation: 1701 Cannot truncate a table
referenced in a foreign key constraint (`app`.`vehicles`, CONSTRAINT `vehic
les_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `app`.`users` (`id`
)) (sql: truncate `users`)
[PDOException]
sqlSTATE[42000]: Syntax error or access violation: 1701 Cannot truncate a table
referenced in a foreign key constraint (`app`.`vehicles`, CONSTRAINT `vehic
les_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `app`.`users` (`id`
))
我查看了这个错误应该是什么意思,并且还发现有examples个其他人遇到同样的问题,甚至只是与使用MySQL及其解决方案有关,但是应用:
DB::statement('SET FOREIGN_KEY_CHECKS=0;'); and
DB::statement('SET FOREIGN_KEY_CHECKS=1;');
在down()中似乎不起作用,当我在MysqL中运行describe时,表格看起来是正确的.
正确命名迁移以确保首先迁移users表,然后确定可以应用外键的车辆,并且正确设置的表表明迁移已运行,但随后发生错误.我删除并重新创建了数据库并再次尝试,结果相同.我也不明白为什么它试图截断数据库的第一个迁移和种子,我不会想到当你试图运行PHP artisan migrate:refresh –seed时会发生这种情况.
// 2015_06_17_100000_create_users_table.PHP
class createusersTable extends Migration
{
public function up()
{
Schema::create('users', function (Blueprint $table) {
$table->increments('id');
$table->string('username', 60)->unique();
$table->string('email', 200)->unique();
$table->string('password', 255);
$table->string('role')->default('user');
$table->rememberToken();
$table->timestamps();
});
}
}
public function down()
{
Schema::drop('users');
}
// 2015_06_17_300000_create_vehicles_table.PHP
class CreateVehiclesTable extends Migration
{
public function up()
{
Schema::create('vehicles', function (Blueprint $table) {
$table->increments('id');
$table->integer('user_id')->unsigned();
$table->string('make');
$table->string('model');
$table->string('year');
$table->string('color');
$table->string('plate');
$table->timestamps();
$table->foreign('user_id')->references('id')->on('users');
});
}
}
public function down()
{
Schema::drop('vehicles');
}
解决方法:
DB::table('some_table')->delete();
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