sqlserver循环

普通while循环

 1 循环5来修改学生信息

循环遍历修改记录 

  DECLARE @i int

    set @i=0
    while @i<5
    BEGIN
    update Student set demo = demo+5 WHERE Uid=@i
    set @i=@i +1
    --PRINT @i
    END

  2   游标循环(没有事务)

               ----游标循环(没有事务)

    BEGIN
    DECLARE @a INT,@error INT
    DECLARE @temp NVARCHAR(50)
    SET @a=1
    SET @error=0
    -----申明游标为uid
    DECLARE order_cursor CURSOR
    FOR (SELECT [Uid] FROM Student)
    -----打开游标
    OPEN order_cursor
    ---- 开始循环游标变量
    
FETCH NEXT FROM order_cursor INTO @temp

    WHILE @@FETCH_STATUS=0 -----返回被FETCH语句执行的最后游标的状态
    BEGIN
    UPDATE student SET Age=15+@a,demo=@a WHERE uid=@temp
    SET @a=@a+1
    SET @error=@error+@@ERROR ------记录每次运行sql后是否正确 0正确
    FETCH NEXT FROM order_cursor INTO @temp -----转到下一个游标,没有会死循环
    END
    CLOSE order_cursor ----关闭游标
    DEALLOCATE order_cursor ---释放游标
    END

3    包含事务

  

---游标循环遍历--
BEGIN
DECLARE @a INT ,@error INT
DECLARE @temp VARCHAR(50)
SET @a=1
SET @error=0
BEGIN TRAN
DECLARE order_cursor CURSOR
FOR(SELECT uid FROM student)
OPEN order_cursor
FETCH NEXT FROM order_cursor INTO @temp
WHILE @@FETCH_STATUS=0 ---返回被fetch语句执行的最后游标的状态
BEGIN
UPDATE student SET age=40+@a,demo=@a WHERE uid=@temp
SET @a=@a+1
SET @error=@error+@@ERROR
FETCH NEXT FROM order_cursor INTO @temp ----转到下一个游标
END
IF(@error=0)
BEGIN
COMMIT TRAN
END
ELSE
BEGIN
ROLLBACK TRAN
END
CLOSE order_cursor
DEALLOCATE order_cursor
END

4  https://blog.csdn.net/lockepeak/article/details/2632904

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