无法在Laravel中创建主键外键关系

Question

我试图在laravel中创建一个主键-外键关系，但我一直遇到这个错误

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`))

我似乎找不到哪里出错了，因为我在查看了SO上的其他答案后，对模式进行了更改。

当我运行php artisan migrate时，上面的错误会弹出，这是一个部分迁移。

任何指向这将是真棒，因为我已经寻找了一段时间的解决方案！

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();

新增：DB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种子程序

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

确保在雇员迁移中引用的表已经存在，以便实际上可以引用它们。您可以通过重命名文件/将您的雇员迁移的文件名中的日期部分更改为在您的部门和工资迁移之后。

你也需要改变

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

到

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

以反映您在工资迁移中使用的相同表名。

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