Question

我的表格中有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。我怎么能这样做？

Answer 1

首先删除外键。感谢Razor获得此提示

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

Answer 2

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

<强>的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);'
    );
}

<强>的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 3

感谢您的回答。帮助我在L5.1中找到这个工作代码：

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();
    });
}

Answer 4

就我而言，我需要将col名称放在一个数组中，否则会出错。

@TestInstance

mysql 5.7 ver

Answer 5

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

Answer 6

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

我假设你使用Illuminate\Database\Schema\Blueprint::primary()来创建users.id。如果是这种情况，那么users.id将是未签名的。因此，您的外键列user_id也必须是未签名的。

Answer 7

在当前迁移中，将无符号函数用于user_id：

$table->interger('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('table_name')->onDelete('cascade');

添加＆＃34; ON DELETE CASCADE＆＃34;到Laravel的现有专栏

7 个答案: