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`
))
我查了一下这个错误应该是什么意思,还发现了其他人遇到同样问题的例子,甚至只是与使用MySQL和他们的解决方案有关,但应用:
DB::statement('SET FOREIGN_KEY_CHECKS=0;'); and
DB::statement('SET FOREIGN_KEY_CHECKS=1;');
在 down() 内似乎不起作用,当我在 MySQL 中运行 describe 时,表看起来正确。
正确命名迁移以确保首先迁移用户表,然后迁移车辆,以便可以应用外键,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在数据库的第一次迁移和种子时截断,我不会想到当你尝试运行 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');
}