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sql 循环写法

青青子衿谈育儿 2022-03-23 阅读 76
sql

1.while 循环

declare @orderNum varchar(255)
create table #ttableName(id int identity(1,1),Orders varchar(255))
declare @n int,@rows int
insert #ttableName(orders) select orderNum from pe_Orders where orderId<50
--select @rows=count(1) from pe_Orders
select @rows =@@rowcount
set @n=1
while @n<=@rows
begin
  select @orderNum=OrderNum from PE_Orders where OrderNum=(select Orders from #ttableName where id=@n)
  print (@OrderNum)
  select @n=@n+1
end
drop table #ttableName

2.游标循环

declare @orderN varchar(50)  --临时变量,用来保存游标值
declare y_curr cursor for   --申明游标 为orderNum
select orderNum from pe_Orders where orderId<50
open y_curr   --打开游标
fetch next from Y_curr into @orderN   ----开始循环游标变量
while(@@fetch_status=0)  ---返回被 FETCH 语句执行的最后游标的状态,而不是任何当前被连接打开的游标的状态。
begin
  print (@orderN)
  update pe_Orders set Functionary+@orderN where orderNum=@orderN   --操作数据库
  fetch next from y_curr into @orderN   --开始循环游标变量
end
close y_curr  --关闭游标
deallocate y_curr   --释放游标

3.带事务的游标循环

select orderNum,userName,MoneyTotal into #t from pe_Orders po
DECLARE @n int,@error int
--set @n=1
set @error=0
BEGIN TRAN   --申明 开始事务
declare @orderN varchar(50),@userN varchar(50)   --临时变量,用来保存游标值
declare y_curr cursor for    --申明游标 为orderNum,userName
select orderNum,userName from PE_Orders where Orderid<50
open y_curr
fetch next from y_curr into @orderN,@userN
while @@fetch_status = 0
BEGIN
  select isnull(sum(MoneyTotal),0),orderNum from #t where username=@userN
  -- set @n=@n+1
  set @error=@error+@@error  --记录每次运行sql后 是否正确 0正确
  fetch next from y_curr into @orderN,@userN
END
IF @error=0
BEGIN
  commit tran   ---事务提交
END
ELSE
BEGIN
  ROLLBACK TRAN   ---事务回滚
END
close y_curr
deallocate y_curr
DROP TABLE #t
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