Question

我想知道是否可以为多个客户端运行脚本，我可以在运行指定客户端时添加额外的where子句，而不必多次重写基本脚本？

EG。基本脚本是

SELECT Status, count(distinct T1.AccountNo)
FROM Orders (nolock), Accounts (NOLOCK)
WHERE Orders.AccountNo = Accounts .AccountNo  
AND date between '1 Oct 2011' and '31 Oct 2011'
GROUP BY Status

但是当我为客户A竞选时，我想要包含额外的标准

AND Accounts.Role IN ('User','Admin')
AND Accounts.Active= 'Y'

Answer 1

SELECT Status, count(distinct T1.AccountNo)
FROM Orders (nolock), Accounts (NOLOCK)
WHERE Orders.AccountNo = Accounts .AccountNo  
AND date between '1 Oct 2011' and '31 Oct 2011'
AND CASE WHEN Client = 'A' THEN Accounts.Role ELSE 'User' END IN ('User', 'Admin')
AND CASE WHEN Client = 'A' THEN Accounts.Active ELSE 'Y' END = 'Y'
GROUP BY Status

Answer 2

在SQL Server上，您可以按如下方式使用HOST_NAME（）：

SELECT Status, count(distinct T1.AccountNo)
FROM Orders (nolock), Accounts (NOLOCK)
WHERE Orders.AccountNo = Accounts .AccountNo  
AND date between '1 Oct 2011' and '31 Oct 2011'
AND ((HOST_NAME() <> 'ClientA') OR (Accounts.Role IN ('User') AND Accounts.Active= 'Y'))
GROUP BY Status

Answer 3

当不需要参数时，您会在存储过程中看到这一点：

SELECT *
FROM SomeTable
WHERE ((@myvariable IS NULL OR @myvariable = mycolumn))

不幸的是，这通常会导致扫描，因为它可能会或可能不会短路。

我要发布的另一个例子与Derek Kromm的相同。

最后你可以使用Dynamic SQL - 人们要么喜欢它，要么讨厌它。

sql where子句仅在包含时才包含

3 个答案: