在Update語句

Question

使用subquerys我有一個觸發以下SQL語句刪除對火災：

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

我的問題是，最後SortOrder指Deleted桌上，而不是到bk2_InfoPages表。我不允許在bk2_InfoPages表中添加別名，因爲它是UPDATE聲明 - 所以我應該怎麼做？

Answer 1

這應該工作：

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

你有別名的表做子查詢，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)