SQL 触发器语法

Question

我数据库中的每门课程都有一个对应的faculty_id。

每个学院都与其他学院有密切关系（因此，具有这些学院 ID 的课程也是如此）。教师关联和课程关联是分开的表格。

我正在尝试构建一个触发器，当faculty_affinity 上的记录被删除时，该触发器会从 course_affinity 表中删除记录。

这就是我所拥有的。它不起作用。

CREATE TRIGGER deleteCourses
AFTER DELETE
ON faculty_affinities
AS
BEGIN
    DELETE FROM course_affinities
    JOIN courses AS course1
    JOIN courses AS course2
    ON course_affinities.course1_id = course1.id
    AND course_affinities.course2_id = course2.id
    WHERE (course1.faculty_id = DELETED.faculty1_id OR course1.faculty_id = DELETED.faculty2_id)
    AND (course2.faculty_id = DELETED.faculty1_id OR course2.faculty_id = DELETED.faculty2_id);
END;

帮助别人？我做错了什么？

编辑：我收到错误

SQLSTATE[4200]: Syntax error... neas 'AS at line 4

Edit2：我的迁移

Schema::create('courses', function (Blueprint $table) {
                $table->increments('id');
                $table->string('name', 150);
                $table->integer('faculty_id')->unsigned();
                $table->foreign('faculty_id')->references('id')->on('faculties');
                $table->boolean('active')->default(1);
                //$table->softDeletes();
            });

    Schema::create('faculties', function (Blueprint $table) {
                    $table->increments('id');
                    $table->string('name', 150)->unique();
                    $table->boolean('active')->default(1);
                    //$table->softDeletes();
            });


Schema::create('course_affinities', function (Blueprint $table) {
                $table->increments('id');
                $table->integer('course1_id')->unsigned();
                    $table->foreign('course1_id')->references('id')->on('courses');
                $table->integer('course2_id')->unsigned();
                    $table->foreign('course2_id')->references('id')->on('courses');
                $table->boolean('active')->default(1);
                //$table->softDeletes();
            });

Schema::create('faculty_affinities', function (Blueprint $table) {
                $table->increments('id');
                $table->integer('faculty1_id')->unsigned();
                    $table->foreign('faculty1_id')->references('id')->on('faculties');
                $table->integer('faculty2_id')->unsigned();
                    $table->foreign('faculty2_id')->references('id')->on('faculties');
                $table->boolean('active')->default(1);
                //$table->softDeletes();
            });

Answer 1

您的代码看起来可能是为 MS SQL Server 而不是 MySQL 编写的（deleted 虚拟表的使用暗示了这一点）；对应的MySQL语法应该如下：

CREATE TRIGGER deleteCourses
AFTER DELETE ON faculty_affinities
FOR EACH ROW
BEGIN
    DELETE ca
    FROM course_affinities ca
    JOIN courses AS course1 ON ca.course1_id = course1.id 
    JOIN courses AS course2 ON ca.course2_id = course2.id    
    WHERE (course1.faculty_id = OLD.faculty1_id OR course1.faculty_id = OLD.faculty2_id)
      AND (course2.faculty_id = OLD.faculty1_id OR course2.faculty_id = OLD.faculty2_id);
END;

虽然我还没有测试过，所以请小心...