添加带有外键的 laravel 迁移

Question

我创建了一个名为“users”的表。有名为“companies”、“designations”、“departments”的表。我想将 company_id、designation_id、department_id 列作为外键添加到 users 表中。

我试过了，但没有用

public function up()
{
    Schema::table('users', function (Blueprint $table) {

        $table->integer('department_id');
        $table->integer('company_id');
        $table->integer('designation_id');

        $table->foreign('department_id')->references('id')->on('departments')->onDelete('restrict')->onUpdate('restrict');
        $table->foreign('company_id')->references('id')->on('companies')->onDelete('restrict')->onUpdate('restrict');
        $table->foreign('designation_id')->references('id')->on('designations')->onDelete('restrict')->onUpdate('restrict');



    });
}


public function down()
{
    Schema::table('users', function (Blueprint $table) {
        $table->dropColumn(['department_id','company_id','designation_id']);
    });
}

当我迁移迁移时，它会显示此错误。

Illuminate\Database\QueryException: SQLSTATE[HY000]: General error: 1005 Can't create table lanwadb 。 users (errno: 150 "Foreign key constraint is wrongly forms") (SQL: alter table users add constraint users_department_id_foreign外键 ( department_id ) 引用departments ( id ) 删除限制更新限制)

指定迁移如下，

public function up()
    {
        Schema::create('designations', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->timestampsTz();
        });
    }

部门迁移如下，

public function up()
    {
        Schema::create('departments', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->integer('company_id');
            $table->timestampsTz();
        });
    }
    ```

Answer 1

用这个：

    $table->integer('department_id')->unsigned()->nullable();
    $table->integer('company_id')->unsigned()->nullable();
    $table->integer('designation_id')->unsigned()->nullable();
    $table->foreign('department_id')->references('id')->on('departments')->onDelete('cascade')->onUpdate('cascade');
    $table->foreign('company_id')->references('id')->on('departments')->onDelete('cascade')->onUpdate('cascade');
    $table->foreign('designation_id')->references('id')->on('departments')->onDelete('cascade')->onUpdate('cascade');

Answer 2

为了建立关系，外键字段应该被index 。 在这里，您要使用三列作为外键'company_id' 、 'department_id'和'designation_id' 。 在 Laravel 迁移中，您可以使用unsigned() function 对它们进行index 。

例子：

$table->integer('department_id')->unsigned();
$table->integer('company_id')->unsigned();
$table->integer('designation_id')->unsigned();

还有另一个名为unsignedInteger()的 function 可以创建一个 Integer 和 Unsigned 列。

$table->unsignedInteger('department_id');
$table->unsignedInteger('company_id');
$table->unsignedInteger('designation_id');