光标内的光标

Question

主要问题是将行的索引更改为1,2,3 ..其中contact-id和type是相同的.但是所有列都可以包含完全相同的数据,因为一些前雇员搞砸了并通过contact-id和type更新所有行.不知何故,有些行没有混乱,但索引行是相同的.这完全是混乱.

我试图使用一个带有来自外部光标的变量的内部游标.但似乎它卡在内部光标中.

查询的一部分如下所示:

Fetch NEXT FROM OUTER_CURSOR INTO @CONTACT_ID,  @TYPE
While (@@FETCH_STATUS <> -1)
BEGIN
IF (@@FETCH_STATUS <> -2)

    DECLARE INNER_CURSOR Cursor 
    FOR 
    SELECT * FROM CONTACTS
    where CONTACT_ID = @CONTACT_ID
    and TYPE = @TYPE 

    Open INNER_CURSOR 

    Fetch NEXT FROM INNER_CURSOR 
    While (@@FETCH_STATUS <> -1)
    BEGIN
    IF (@@FETCH_STATUS <> -2)

可能是什么问题？是@@ FETCH_STATUS暧昧还是什么？

编辑:如果我不在内部游标内使用此代码,一切看起来很好:

UPDATE CONTACTS
SET INDEX_NO = @COUNTER
where current of INNER_CURSOR

编辑:这是大局:

BEGIN TRAN

DECLARE @CONTACT_ID VARCHAR(15)
DECLARE @TYPE VARCHAR(15)
DECLARE @INDEX_NO  SMALLINT
DECLARE @COUNTER SMALLINT
DECLARE @FETCH_STATUS INT 

DECLARE OUTER_CURSOR CURSOR 

FOR 

SELECT CONTACT_ID, TYPE, INDEX_NO FROM CONTACTS
WHERE  
CONTACT_ID IN (SELECT CONTACT_ID FROM dbo.CONTACTS
WHERE CONTACT_ID IN(...)
GROUP BY CONTACT_ID, TYPE, INDEX_NO
HAVING COUNT(*) > 1

OPEN OUTER_CURSOR 

FETCH NEXT FROM OUTER_CURSOR INTO @CONTACT_ID,  @TYPE, @INDEX_NO
WHILE (@@FETCH_STATUS <> -1)
BEGIN
IF (@@FETCH_STATUS <> -2)

SET @COUNTER = 1

        DECLARE INNER_CURSOR CURSOR 
        FOR 
        SELECT * FROM CONTACTS
        WHERE CONTACT_ID = @CONTACT_ID
        AND TYPE = @TYPE 
        FOR UPDATE 

        OPEN INNER_CURSOR 

        FETCH NEXT FROM INNER_CURSOR 

        WHILE (@@FETCH_STATUS <> -1)
        BEGIN
        IF (@@FETCH_STATUS <> -2)

        UPDATE CONTACTS
        SET INDEX_NO = @COUNTER
        WHERE CURRENT OF INNER_CURSOR

        SET @COUNTER = @COUNTER + 1

        FETCH NEXT FROM INNER_CURSOR 
        END
        CLOSE INNER_CURSOR
        DEALLOCATE INNER_CURSOR

FETCH NEXT FROM OUTER_CURSOR INTO @CONTACT_ID,  @TYPE, @INDEX_NO
END
CLOSE OUTER_CURSOR
DEALLOCATE OUTER_CURSOR

COMMIT TRAN

Answer 1

你有各种各样的问题.首先,为什么要使用特定的@@ FETCH_STATUS值？它应该是@@ FETCH_STATUS = 0.

其次,你不选择你的内心光标到任何东西.而且我想不出你会以这种方式选择所有领域的任何情况 - 将它们拼出来!

这是一个经过的样本.Folder的主键为"ClientID",也是Attend的外键.我只是打印所有的Attend UID,按文件夹ClientID分类:

Declare @ClientID int;
Declare @UID int;

DECLARE Cur1 CURSOR FOR
    SELECT ClientID From Folder;

OPEN Cur1
FETCH NEXT FROM Cur1 INTO @ClientID;
WHILE @@FETCH_STATUS = 0
BEGIN
    PRINT 'Processing ClientID: ' + Cast(@ClientID as Varchar);
    DECLARE Cur2 CURSOR FOR
        SELECT UID FROM Attend Where ClientID=@ClientID;
    OPEN Cur2;
    FETCH NEXT FROM Cur2 INTO @UID;
    WHILE @@FETCH_STATUS = 0
    BEGIN
        PRINT 'Found UID: ' + Cast(@UID as Varchar);
        FETCH NEXT FROM Cur2 INTO @UID;
    END;
    CLOSE Cur2;
    DEALLOCATE Cur2;
    FETCH NEXT FROM Cur1 INTO @ClientID;
END;
PRINT 'DONE';
CLOSE Cur1;
DEALLOCATE Cur1;

最后,你SURE你想要做这样的事情在存储过程中？滥用存储过程非常容易,并且通常会反映出表征问题的问题.例如,我给出的样本使用标准选择调用可以更容易地完成.

Answer 2

您还可以通过完全避免游标来回避嵌套游标问题,常规游标问题和全局变量问题.

declare @rowid int
declare @rowid2 int
declare @id int
declare @type varchar(10)
declare @rows int
declare @rows2 int
declare @outer table (rowid int identity(1,1), id int, type varchar(100))
declare @inner table (rowid int  identity(1,1), clientid int, whatever int)

insert into @outer (id, type) 
Select id, type from sometable

select @rows = count(1) from @outer
while (@rows > 0)
Begin
    select top 1 @rowid = rowid, @id  = id, @type = type
    from @outer
    insert into @innner (clientid, whatever ) 
    select clientid whatever from contacts where contactid = @id
    select @rows2 = count(1) from @inner
    while (@rows2 > 0)
    Begin
        select top 1 /* stuff you want into some variables */
        /* Other statements you want to execute */
        delete from @inner where rowid = @rowid2
        select @rows2 = count(1) from @inner
    End  
    delete from @outer where rowid = @rowid
    select @rows = count(1) from @outer
End

Answer 3

我不完全理解“更新游标当前”的问题是什么，但通过对内部游标使用两次 fetch 语句可以解决该问题：

FETCH NEXT FROM INNER_CURSOR

WHILE (@@FETCH_STATUS <> -1)
BEGIN

UPDATE CONTACTS
SET INDEX_NO = @COUNTER
WHERE CURRENT OF INNER_CURSOR

SET @COUNTER = @COUNTER + 1

FETCH NEXT FROM INNER_CURSOR
FETCH NEXT FROM INNER_CURSOR
END