在 TSQL 中,我想将以下代码从必须使用硬编码 dhome 更改为使用循环进行优化。我尝试添加循环失败的尝试也包括在内。
Declare @dhome Tinyint, @bp smallint, @lr smallint, @q smallint
// Set @dhome = 1
While(@dhome <= 3) // My attempt to add a loop
SELECT @lr = MAX(NQdDate), @q = NQd
FROM NQdHistory
WHERE dhomeId = @dhome
GROUP BY NQdDate, NQd
SELECT @bd = COUNT(*)
FROM bdhome
WHERE NQdDate= @lr AND dhomeID= @dhome
DELETE FROM ND1 WITH(XLOCK)
WHERE dhomeID= @dhome AND NQdDate= @lr
UPDATE NQdHistory
SET Nbd = @q - @@RowCount - @bp, NBd = @bp
WHERE NQdDate= @lr AND dhomeID= @dhome
Set @dhome = @dhome +1 //My attempt to end a loop
最佳答案
你走在正确的道路上。你错过了开始和结束。另外,请务必为 @dhome
指定一个值。看来您开始在第三行注释掉它:
Declare @dhome Tinyint, @bp smallint, @lr smallint, @q smallint
// Set @dhome = 1
While(@dhome <= 3) // My attempt to add a loop
begin
SELECT @lr = MAX(NQdDate), @q = NQd
FROM NQdHistory
WHERE dhomeId = @dhome
GROUP BY NQdDate, NQd
SELECT @bd = COUNT(*)
FROM bdhome
WHERE NQdDate= @lr AND dhomeID= @dhome
DELETE FROM ND1 WITH(XLOCK)
WHERE dhomeID= @dhome AND NQdDate= @lr
UPDATE NQdHistory
SET Nbd = @q - @@RowCount - @bp, NBd = @bp
WHERE NQdDate= @lr AND dhomeID= @dhome
Set @dhome = @dhome +1 //My attempt to end a loop
end
如果您熟悉 C/C#/C++,可以将 T-SQL 的 Begin 和 End 想象为大括号 {
和 }
(如果您更熟悉)使用 VB Then
和 End If
。或者更像 pascals Begin
和 End
。你明白了:)
关于tsql - 如何在 SQL 中使用循环?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15770973/