sol如何解决此数据库迁移问题？

Question

我在Laravel数据库迁移方面遇到麻烦。 我在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，它显示此错误消息。

Illuminate \\ Database \\ QueryException：SQLSTATE [42000]：语法错误或访问冲突：1064 SQL语法错误； 检查对应于您MariaDB的服务器版本，在1号线“上更新级联删除级联）”使用附近的正确语法手册（SQL：ALTER TABLE education_qualifications添加约束education_qualifications_teacher_id_foreign外键（ teacher_id ）引用teachers （）上删除级联在更新级联上）：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；请在删除级联上检查与您的MariaDB服务器版本相对应的手册以在'）附近使用正确的语法。更新级联'在第1行“）E：\\ XAMPP \\ htdocs \\ ViduresaApp \\ vendor \\ laravel \\ framework \\ src \\ Illuminate \\ Database \\ Connection.php：452

2 PDO :: prepare（“在更新级联上删除级联时，更改表education_qualifications添加约束education_qualifications_teacher_id_foreign外键（ teacher_id ）引用teachers （）”）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

您可以在同一行上同时使用onupdate和ondelete

例如：

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