改进此SQL查询以获得更好的性能

DBA不喜欢我正在使用case语句和子查询。我可以采取另一种方法来提高性能吗？此更新语句是存储过程的一部分。改进此SQL查询以获得更好的性能

UPDATE dbo.CMN_PersonsFerpa 
    SET 
     IsWorkEmailFerpa = (CASE WHEN (SELECT EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID) = 'Work' THEN @IsFERPA ELSE IsWorkEmailFerpa END, 
     IsPersonalEmailFerpa = (CASE WHEN (SELECT EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID) = 'Personal' THEN @IsFERPA ELSE IsPersonalEmailFerpa END, 
     IsParentEmailFerpa = (CASE WHEN (SELECT EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID) = 'Parent' THEN @IsFERPA ELSE IsParentEmailFerpa END, 
     IsTempEmailFerpa = (CASE WHEN (SELECT EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID) = 'Temporary' THEN @IsFERPA ELSE IsTempEmailFerpa END, 
     IsFAFSAEmailFerpa = (CASE WHEN (SELECT EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID) = 'FAFSA' THEN @IsFERPA ELSE IsFAFSAEmailFerpa END, 
     IsCSSProfEmailFerpa = (CASE WHEN (SELECT EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID) = 'CSS Profile' THEN @IsFERPA ELSE IsCSSProfEmailFerpa END, 
     IsCommenceEmailFerpa = (CASE WHEN (SELECT EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID) = 'Commencement' THEN @IsFERPA ELSE IsCommenceEmailFerpa END, 
     IsAcctHoldEmailFerpa = (CASE WHEN (SELECT EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID) = 'Account Holder' THEN @IsFERPA ELSE IsAcctHoldEmailFerpa END 
    Where CMN_PersonsFerpa.cmn_personsID = (select cmn_personsID from CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID)

在这里有几个建议是我有。这可以接受吗？还是有更好的办法？：

SELECT @DBType = EmailType, @cmn_personsID = CMN_PersonsID FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID 

    UPDATE dbo.CMN_PersonsFerpa 
    SET 
     IsWorkEmailFerpa = CASE WHEN @DBType = 'Work' THEN @IsFERPA END, 
     IsPersonalEmailFerpa = CASE WHEN @DBType = 'Personal' THEN @IsFERPA END, 
     IsParentEmailFerpa = CASE WHEN @DBType = 'Parent' THEN @IsFERPA END, 
     IsTempEmailFerpa = CASE WHEN @DBType = 'Temporary' THEN @IsFERPA END, 
     IsFAFSAEmailFerpa = CASE WHEN @DBType = 'FAFSA' THEN @IsFERPA END, 
     IsCSSProfEmailFerpa = CASE WHEN @DBType = 'CSS Profile' THEN @IsFERPA END, 
     IsCommenceEmailFerpa = CASE WHEN @DBType = 'Commencement' THEN @IsFERPA END, 
     IsAcctHoldEmailFerpa = CASE WHEN @DBType = 'Account Holder' THEN @IsFERPA END, 
     LastChangeBy = @UserGUID, 
     LastChangeDateTime = GETDATE() 
      Where CMN_PersonsFerpa.cmn_personsID = @CMN_PersonsID

来源

2014-09-24 NonProgrammer

@CMN_PersonsEmailLinksID从哪里来？它是否从CMN_PersonsFerpa中拉出来？ – Malk 2014-09-24 21:00:38

@CMN_PersonsEmailLinksID来自前端而不是任何表。 – NonProgrammer 2014-09-24 21:04:58

目标是消除子查询。您可以通过在更新之前构建临时表或使用适当的链接来完成此操作。不知道你的数据模式很难帮你设计一些东西，但这里是一个镜头：

update p set 
    IsWorkEmailFerpa = case when e.EmailType = 'Work' then @IsFERPA else IsWorkEmailFerpa end, 
    IsPersonalEmailFerpa = case when e.EmailType = 'Personal' then @IsFERPA else IsPersonalEmailFerpa end, 
    IsParentEmailFerpa = case when e.EmailType = 'Parent' then @IsFERPA else IsParentEmailFerpa end, 
    IsTempEmailFerpa = case when e.EmailType = 'Temporary' then @IsFERPA else IsTempEmailFerpa end, 
    ... 
    IsAcctHoldEmailFerpa = case when e.EmailType = 'Account Holder' then @IsFERPA else IsAcctHoldEmailFerpa end, 
from dbo.CMN_PersonsFerpa p 
    join dbo.CMN_PersonsEmailLinks e 
     on e.cmn_personsID = p.cmn_personsID 
where e.CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID

来源

2014-09-24 21:14:39 Malk

而不是运行查询8次，运行它一旦进入一个变量，该变量本身的执行情况。

会是这个样子：

SELECT @EmailType = EmailType FROM dbo.CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID 

UPDATE dbo.CMN_PersonsFerpa 
    SET 
     IsWorkEmailFerpa = (CASE WHEN @EmailType = 'Work' THEN @IsFERPA ELSE IsWorkEmailFerpa END, 
     IsPersonalEmailFerpa = (CASE WHEN @EmailType = 'Personal' THEN @IsFERPA ELSE IsPersonalEmailFerpa END, 
     IsParentEmailFerpa = (CASE WHEN @EmailType = 'Parent' THEN @IsFERPA ELSE IsParentEmailFerpa END, 
     IsTempEmailFerpa = (CASE WHEN @EmailType = 'Temporary' THEN @IsFERPA ELSE IsTempEmailFerpa END, 
     IsFAFSAEmailFerpa = (CASE WHEN @EmailType = 'FAFSA' THEN @IsFERPA ELSE IsFAFSAEmailFerpa END, 
     IsCSSProfEmailFerpa = (CASE WHEN @EmailType = 'CSS Profile' THEN @IsFERPA ELSE IsCSSProfEmailFerpa END, 
     IsCommenceEmailFerpa = (CASE WHEN @EmailType = 'Commencement' THEN @IsFERPA ELSE IsCommenceEmailFerpa END, 
     IsAcctHoldEmailFerpa = (CASE WHEN @EmailType = 'Account Holder' THEN @IsFERPA ELSE IsAcctHoldEmailFerpa END 
    Where CMN_PersonsFerpa.cmn_personsID = (select cmn_personsID from CMN_PersonsEmailLinks WHERE CMN_PersonsEmailLinksID = @CMN_PersonsEmailLinksID)

来源

2014-09-24 21:01:20

-1如果EmailType在SELECT之后但UPDATE之前更改，会怎么样？ – Anon 2014-09-24 22:06:33

你为什么不使用连接？相关的子查询像光标一样一行一行地工作，几乎从不应该使用。

来源

2014-09-24 21:11:12 HLGEM

改进此SQL查询以获得更好的性能

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