在Update语句

Question

使用subquerys我有一个触发以下SQL语句删除对火灾：

UPDATE bk2_InfoPages 
SET SortOrder = SortOrder - (SELECT COUNT(*) FROM Deleted d WHERE d.SortOrder <= SortOrder) 

我的问题是，最后SortOrder指Deleted桌上，而不是到bk2_InfoPages表。我不允许在bk2_InfoPages表中添加别名，因为它是UPDATE声明 - 所以我应该怎么做？

Answer 1

这应该工作：

UPDATE b 
SET SortOrder = SortOrder - 
    (SELECT COUNT(*) FROM Deleted d WHERE d.SortOrder <= b.SortOrder) 
from bk2_InfoPages b 

你有别名的表做子查询，例如：

-- this executes fine 
create table #t (t int) 

update t 
set t = (select count(*) from #t t1 where t.t = t1.t) 
from #t t 

Answer 2

UPDATE bk2_InfoPages 
SET SortOrder = SortOrder - (SELECT COUNT(*) FROM Deleted d WHERE d.SortOrder <= bk2_InfoPages.SortOrder)