Laravel 在迁移中删除外键

Question

我想创建一个 Migration，它将删除一个 table。我这样创建了迁移：

Schema::table('devices', function (Blueprint $table) {
    $table->increments('id');
    $table->unsignedInteger('client_id')->nullable();
    $table->foreign('client_id')->references('id')->on('clients')->onDelete('cascade');
});

现在我试着这样放下它：

    Schema::table('devices', function (Blueprint $table) {
        $table->dropForeign('devices_client_id_foreign');
        $table->drop('devices');
    });

但是我得到以下错误：

In Connection.php line 664:

  SQLSTATE[42000]: Syntax error or access violation: 1091 Can't DROP 'devices_client_id_foreign'; check that column/key exists (SQL:

alter table devices drop foreign key devices_client_id_foreign)

In PDOStatement.php line 144:

  SQLSTATE[42000]: Syntax error or access violation: 1091 Can't DROP 'devices_client_id_foreign'; check that column/key exists


In PDOStatement.php line 142:

  SQLSTATE[42000]: Syntax error or access violation: 1091 Can't DROP 'devices_client_id_foreign'; check that column/key exists

Answer 1

只需放下整个 table (documentation):

Schema::drop('devices');

Answer 2

试试这个方法...

  public function down()
 {
    Schema::dropIfExists('devices');
 }

//Or this
  public function down(){
    Schema::table('devices', function (Blueprint $table) {
        $table->dropForeign(['client_id']);
        $table->dropColumn('client_id');
        $table->drop('devices');
    });
  }

Answer 3

您只需要在删除 table 之前禁用外键检查，然后像这样再次启用它们：

DB::statement('SET FOREIGN_KEY_CHECKS=0;');
Schema::dropIfExists('devices');
DB::statement('SET FOREIGN_KEY_CHECKS=1;');

Answer 4

你可以使用这个答案。

将列名作为数组传递给 dropForeign。在内部，Laravel 删除关联的外键。

$table->dropForeign(['client_id']);

Laravel 在迁移中删除外键

Laravel drop foreign Key in Migration

php

mysql

laravel

laravel-5.6