sol如何解决这个数据库迁移问题？

Question

我在进行 Laravel 数据库迁移时遇到问题。我在我的数据库迁移文件中输入了外键约束，但是当我尝试迁移文件时，它显示了这个错误消息。

Illuminate\Database\QueryException : SQLSTATE[42000]: 语法错误或访问冲突：1064 您的 SQL 语法有错误；检查与您的 MariaDB 服务器版本相对应的手册，以在第 1 行（SQL：alter table education_qualifications add constraint education_qualifications_teacher_id_foreign foreign key (teacher_id) 参考中的 delete cascade on update cascade' 附近使用正确的语法teachers () on delete cascade on update cascade) at E:\XAMPP\htdocs\ViduresaApp\vendor\laravel\framework\src\Illuminate\Database\Connection.php:664

    660|         // If an exception occurs when attempting to run a query, we'll format the error
    661|         // message to include the bindings with SQL, which will make this exception a
    662|         // lot more helpful to the developer instead of just the database's errors.
    663|         catch (Exception $e) {
  > 664|             throw new QueryException(
    665|                 $query, $this->prepareBindings($bindings), $e
    666|             );
    667|         }
    668|

异常跟踪：

1 PDOException::("SQLSTATE[42000]: 语法错误或访问冲突：1064 您的 SQL 语法有错误；请查看与您的 MariaDB 服务器版本相对应的手册，了解在 ') 附近使用的正确语法在第 1 行更新级联时删除级联") E:\XAMPP\htdocs\ViduresaApp\vendor\laravel\framework\src\Illuminate\Database\Connection.php:452

2 PDO::prepare("修改表education_qualifications添加约束education_qualifications_teacher_id_foreign外键(teacher_id)引用teachers() on delete cascade on update cascade") E:\XAMPP\htdocs\ViduresaApp\vendor\laravel\framework\src\Illuminate\Database\Connection.php:452

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateEducationQualificationsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {

        Schema::create('education_qualifications', function (Blueprint $table) {
            $table->increments('id');
            $table->unsignedInteger('teacher_id')->nullable();
            $table->unsignedInteger('student_id')->nullable();
            $table->string('institute_name');
            $table->string('user_degree');
            $table->string('field_of_study');
            $table->string('user_grade');
            $table->date('from_date')->nullable();
            $table->date('to_date')->nullable();
            $table->text('edu_description');
            $table->timestamps();

            $table->foreign('teacher_id')->references('id')->on('teachers')->onUpdate('cascade')->onDelete('cascade');
            $table->foreign('student_id')->references('id')->on('users')->onUpdate('cascade')->onDelete('cascade');

            $table->primary(['teacher_id', 'student_id']);

        });

    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('education_qualifications');
    }
}

Answer 1

你可以在同一行同时使用 onupdate 和 ondelete

例如：

$table->foreign(’author’)->references(’id’)->on(’users’)->onUpdate(’cascade’);