帮忙看看这段sql执行没效果？
use whinfo2004

DECLARE @txxid int,@personid int,@lxfs int

DECLARE authors_cursor CURSOR FOR
SELECT id,personid,lxfsid
FROM dbo.scl_txx
WHERE (personid <> - 1)

OPEN authors_cursor

FETCH NEXT FROM authors_cursor
INTO @txxid, @personid, @lxfs
--按理说这里不需要加这段处理，但是不加就执行不过去
print @txxid
if (@lxfs=null)
BEGIN
update dbo.scl_txx set lxfsid= '-1 '
where id=@txxid
END
----
WHILE (@@FETCH_STATUS = 0 )

BEGIN
FETCH NEXT FROM authors_cursor
INTO @txxid, @personid, @lxfs

print @txxid

IF (@lxfs=null)
BEGIN
UPDATE dbo.scl_txx SET lxfsid=-1
WHERE id=@txxid
END

END

在sql2005SP2环境下，执行成功，但是数据并没发生变化，高手看看那里出错了，谢谢！

[解决办法]
if (@lxfs is null)
[解决办法]
print @txxid
if (@lxfs=null)
BEGIN
update dbo.scl_txx set lxfsid= '-1 '
where id=@txxid
END

以上放在WHILE (@@FETCH_STATUS = 0 )之后
[解决办法]
在里：
if (@lxfs=null)改if (@lxfs is null)

DECLARE @NULL VARCHAR(10)
SET @NULL = NULL

IF (@NULL IS NULL)
PRINT 'IS NULL '
ELSE
PRINT 'NOT NULL '+@NULL
[解决办法]
use whinfo2004
GO
DECLARE @txxid int,@personid int,@lxfs int

DECLARE authors_cursor CURSOR FOR
SELECT id,personid,lxfsid
FROM dbo.scl_txx
WHERE (personid <> - 1)

OPEN authors_cursor

FETCH NEXT FROM authors_cursor
INTO @txxid, @personid, @lxfs

WHILE (@@FETCH_STATUS=0)
BEGIN
if (@lxfs IS null)
BEGIN
update dbo.scl_txx set lxfsid= '-1 '
where id=@txxid
END

IF (@lxfs IS null)
BEGIN
UPDATE dbo.scl_txx SET lxfsid=-1
WHERE id=@txxid
END

FETCH NEXT FROM authors_cursor
INTO @txxid, @personid, @lxfs
END
CLOSE authors_cursor
DEALLOCATE authors_cursor