将光标与CTE一起使用 [英] Using a cursor with a CTE

问题描述

我需要一个游标用于以下查询，因此我可以循环访问以获取/更新/插入一些其他数据。有人可以帮我吗？

I need a cursor for the below query so I can loop through to fetch/update/insert some other data. Can somebody help me with this?

DECLARE @FROMDATE DATETIME
DECLARE @TODATE DATETIME
SELECT @FROMDATE = Getdate()
SELECT @TODATE = Getdate() + 7

;WITH DATEINFO(DATES)
     AS (SELECT @FROMDATE
         UNION ALL
         SELECT DATES + 1
         FROM   DATEINFO
         WHERE  DATES < @TODATE)
SELECT *
FROM   DATEINFO
OPTION (MAXRECURSION 0)

我尝试了很多方法，但没有找到任何可行的方法。

I tried so many ways, but didn't find any that worked.

我正在使用

declare @adate datetime
DECLARE @FROMDATE DATETIME 
DECLARE @TODATE DATETIME 
select @FROMDATE=getdate()
select @TODATE =getdate()+7

declare @weekdates cursor for
WITH DATEINFO(DATES) AS (SELECT @FROMDATE UNION ALL SELECT DATES + 1 FROM DATEINFO WHERE DATES < @TODATE) 
SELECT * FROM DATEINFO OPTION (MAXRECURSION 0)

open @weekdates
fetch next from @weekdates into @adate
while @@fetch_status=0
begin
print 'success'
fetch next from @weekdates into @adate
end
close @weekdates
deallocate @weekdates

仍然出现错误

推荐答案

只需将其放在通用表表达式之前：

Just put it in before the common table expression:

DECLARE @FROMDATE DATETIME 
DECLARE @TODATE DATETIME 
select @FROMDATE=getdate()
select @TODATE =getdate()+7

declare boris cursor for

WITH DATEINFO(DATES)
     AS (SELECT @FROMDATE
         UNION ALL
         SELECT DATES + 1
         FROM   DATEINFO
         WHERE  DATES < @TODATE)
SELECT *
FROM   DATEINFO
OPTION (MAXRECURSION 0) 

（但是，插入关于游标的常规警告几乎总是错误地完成工作。如果您可以找到一种基于集合的方式进行整个操作的方法，通常是更可取的，并且可能会表现更好（或至少更适合进行性能调整））

(However, insert usual cautions about cursors almost always being the wrong tool for the job. If you can find a way to do the whole operation in a set based manner, it's usually preferable, and likely to perform better (or at least be more amenable to performance tuning))

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