TransactSQL insert触发器 游标遍历结果集

student 表 -course 表 student-course 关系表

当insert student的时候在关系表里添加student和course的关系。由于course是必修课，所以属于同一个major的student和course要默认选择。即student必须选择major的course。

--创建insert插入类型触发器
if (object_id('tgr_student_insert', 'tr') is not null)
    drop trigger tgr_student_insert
GO

    create trigger tgr_student_insert
    on student
        for insert --插入触发
    as
    --定义变量
    declare @studentid int, @name varchar(20), @major int;
    --在inserted表中查询已经插入记录信息
    select @studentid = id, @name = name ,@major =     majorID from inserted;
--    set @name = @name + convert(varchar, @id);
    --set @temp = @id / 2;  
    DECLARE @courseid int;
    DECLARE contact_cursor CURSOR FOR
    select id from course where majorID = @major;
    
    OPEN contact_cursor;
    
    -- Perform the first fetch and store the values in variables.
    -- Note: The variables are in the same order as the columns
    -- in the SELECT statement. 

    FETCH NEXT FROM contact_cursor
    INTO @courseid;

    -- Check @@FETCH_STATUS to see if there are any more rows to fetch.
    WHILE @@FETCH_STATUS = 0
    BEGIN

    -- Concatenate and display the current values in the variables.
    --PRINT 'Course Name: ' + @courseid 
    INSERT INTO student_course (course_id,student_id) VALUES(@courseid,@studentid);
    -- This is executed as long as the previous fetch succeeds.
    FETCH NEXT FROM contact_cursor
    INTO @courseid;
    END

    CLOSE contact_cursor;
    DEALLOCATE contact_cursor;
    
    GO