无法在 Laravel 中创建主键-外键关系

Question

我正在尝试在 laravel 中创建主键-外键关系，但我不断收到此错误

SQLSTATE[HY000]: General error: 1005 Can't create table `volga_2`.`employees` (errno: 150 "Foreign key constraint is incorrectly formed") (SQL: alter table `employees` add constraint `employees_dept_id_foreign` foreign key (`dept_id`) references `departments` (`id`))

在查看 SO 上的其他答案后，我似乎无法找出我哪里出错了，因为我已经对架构进行了更改。

当我运行php artisan migrate 时，会弹出上述错误，并且是部分迁移。

任何指向这个的指针都会很棒，因为我一直在寻找解决这个问题的方法！

谢谢！

员工表

Schema::create('employees', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->integer('dept_id')->unsigned();
            $table->foreign('dept_id')->references('id')->on('departments');
            $table->integer('salary_id')->unsigned();
            $table->foreign('salary_id')->references('id')->on('salary');
            $table->string('name');
            $table->string('gender');
            $table->timestamp('date_of_joining');
            $table->dateTime('date_of_birth');
            $table->timestamps();

部门表

Schema::create('departments', function (Blueprint $table) {
        $table->increments('id');
        $table->string('dept_name');
        $table->timestamps();

工资表

Schema::create('salaries', function (Blueprint $table) {
            $table->increments('id');
            $table->string('monthlySalary');
            $table->timestamps();

添加： 数据库播种机。

factory(App\Employee::class, 25)->create()->each(function ($employee) {
            $department = factory(App\Department::class)->make();
            $employee->department()->save($department);
            $salary = factory(App\Salary::class)->make();
            $employee->salary()->save($salary);
        });

根据评论更改了 DB Seeder

factory(App\Department::class, 10)->create()->each(function ($department) {
            $salary = factory(App\Salary::class)->make();
            $department->salary()->save($salary);
            $employee = factory(App\Employee::class)->make();
            $salary->employee->save($employee);
        });

Answer 1

确保您在 employees 迁移中引用的表已经存在，因此可以实际引用它们。您可以通过重命名文件/更改 employees 迁移文件名中的日期部分来执行此操作，使其位于 departments 和 salaries 迁移之后。

你也需要改变

$table->foreign('salary_id')->references('id')->on('salary');

到

$table->foreign('salary_id')->references('id')->on('salaries');

以反映您在 salaries 迁移中使用的相同表名。

https://laravel.com/docs/5.8/migrations#foreign-key-constraints