SQL 中的这个嵌套 WHILE 循环有什么问题
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What is wrong with this nested WHILE loop in SQL
提问by edosoft
I ran into a weird situation today doing some one-time sql code. This nested loop doesn't seem to run the outer loop: it prints (0,0),(0,1),(0,2) and (0,3)
我今天在做一些一次性 sql 代码时遇到了一种奇怪的情况。这个嵌套循环似乎没有运行外循环：它打印 (0,0)、(0,1)、(0,2) 和 (0,3)
declare @i int, @j int
select @i = 0, @j = 0
while @i < 3 begin
while @j < 3 begin
select @i as i, @j as j
set @j = @j + 1
end
set @i = @i + 1
end
Am I missing something blatantly obvious?
我是否遗漏了一些显而易见的东西？
回答by almog.ori
You are not resetting your j var for the next iteration
您不会为下一次迭代重置 j var
set @i = @i + 1
set @j = 0
回答by ozczecho
You are not resetting @j.
您没有重置@j。
回答by Chjquest
declare @i int, @j int
select @i = 0, @j = 0 --<- Wrong place set @j
while @i < 3
begin
select @i, @j --<-test print, then you will know what happened~
--set @j = 0 --<- Right place to set @j
while @j < 3
begin
select @i as i, @j as j
set @j = @j + 1
end
set @i = @i + 1
end
The original result is 0/0 0/0 0/1 0/2 1/3 2/3
原来的结果是 0/0 0/0 0/1 0/2 1/3 2/3
Well, the above answered, just add code for more detail, lol~
嗯，上面已经回答了，添加代码更详细，lol~
