将"ON DELETE CASCADE"添加到Laravel中的现有列

Question

我的表中有user_id fk列

$table->foreign('user_id')->references('id')->on('users');

我应该在现有列上添加级联删除功能.我怎样才能做到这一点？

Answer 1

先删掉外键.感谢Razor的提示

$table->dropForeign('answers_user_id_foreign');
$table->foreign('user_id')
->references('id')->on('users')
->onDelete('cascade');

Answer 2

就我而言，我需要将 col 名称放在一个数组中，否则会出错。

Schema::table('transactions', function (Blueprint $table) {
    $table->dropForeign(['transactions_order_id_foreign']);
    $table->foreign('order_id')
        ->references('id')->on('orders')
        ->onDelete('cascade')
        ->change();
});

mysql 5.7 版本

Answer 3

$table->foreign('user_id')
      ->references('id')->on('users')
      ->onDelete('cascade');

Answer 4

Laravel 模式构建器无法修改当前状态下的列，因此您将使用原始查询。您将不得不删除并重新创建约束：

PostgreSQL

function up()
{
    DB::statement('alter table answers drop constraint answers_user_id_foreign,
                   add constraint answers_user_id_foreign
                   foreign key (user_id)
                   references users(id)
                   on delete cascade;'
    );
}
function down()
{
    DB::statement('alter table answers drop constraint answers_user_id_foreign,
                   add constraint answers_user_id_foreign
                   foreign key (user_id)
                   references users(id);'
    );
}

MySQL

function up()
{
    DB::statement('alter table answers drop FOREIGN KEY answers_user_id_foreign;');
    DB::statement('alter table answers add constraint answers_user_id_foreign
                   foreign key (user_id)
                   references users(id)
                   on delete cascade;'
    );
}
function down()
{
    DB::statement('alter table answers drop FOREIGN KEY answers_user_id_foreign;');
    DB::statement('alter table answers add constraint answers_user_id_foreign
                   foreign key (user_id)
                   references users(id);'
    );
}

Answer 5

感谢您的提问。帮助我在 L5.1 中获取此工作代码：

public function up()
{
    Schema::table('transactions', function (Blueprint $table) {
        $table->dropForeign('transactions_order_id_foreign');
        $table->foreign('order_id')
            ->references('id')->on('orders')
            ->onDelete('cascade')
            ->change();
    });

    Schema::table('orders', function (Blueprint $table) {
        $table->dropForeign('orders_user_id_foreign');
        $table->foreign('user_id')
            ->references('id')->on('users')
            ->onDelete('cascade')
            ->change();
    });
}