Question

SELECT     
    tbStok.sModel AS Kod, tbStok.sAciklama AS Adı, 
    SF.lFiyat AS SF, PSF.lFiyat AS PSF, 
    TL.lFiyat AS TL , USD.lFiyat AS USD
FROM         
    tbStok 
LEFT JOIN 
    tbStokFiyati AS TL ON tbStok.nStokID =  TL.nStokID 
LEFT JOIN 
    tbStokFiyati AS SF ON tbStok.nStokID =  SF.nStokID
LEFT JOIN 
    tbStokFiyati AS PSF ON tbStok.nStokID = PSF.nStokID 
LEFT JOIN 
    tbStokFiyati AS USD ON tbStok.nStokID = USD.nStokID
GROUP BY 
    tbStok.sModel, tbStok.sAciklama, SF.lFiyat, PSF.lFiyat, TL.lFiyat,USD.lFiyat

上面是我正在使用的SQL语句。

当查询开始时，结果是7255470行，但我在tBstok表中有18867行。

我们在tbStok表中包含产品信息，其中包含2个不同的列，例如产品代码和产品名称。在另一个名为tbStokFiyati的表中，我需要有4个不同的列。

结果很慢！

Answer 1

表格需要与tbStokFiyati分开。


SELECT     
    tbStok.sModel AS Kod, tbStok.sAciklama AS Adı, 
    SF.lFiyat AS SF, PSF.lFiyat AS PSF, 
    TL.lFiyat AS TL , USD.lFiyat AS USD  
FROM   tbStok 

LEFT JOIN 
    tbStokFiyati AS TL ON tbStok.nStokID =  TL.nStokID 
                      and TL.sFiyatTipi='TL'

LEFT JOIN tbStokFiyati AS SF ON tbStok.nStokID =  SF.nStokID
                      and SF.sFiyatTipi='SF'

LEFT JOIN tbStokFiyati AS PSF ON tbStok.nStokID = PSF.nStokID 
                      and PSF.sFiyatTipi='PSF'

LEFT JOIN tbStokFiyati AS USD ON tbStok.nStokID = USD.nStokID
                      and USD.sFiyatTipi='USD'

GROUP BY 
    tbStok.sModel, tbStok.sAciklama, SF.lFiyat, PSF.lFiyat, TL.lFiyat,USD.lFiyat

Answer 2

在运行此类性能问题时，您应该重新审视的第一件事是数据库设计。是否已相应定义PK？您是否在每个FK上创建了非聚集索引来查看联接？您是否在查询中使用的有趣列上创建了索引？您可以在SQL Server Management Studio上使用一项名为 实际执行计划 的功能来检查查询性能出了什么问题。

请查看SQL Server Index Basics以获取进一步的参考还有一些用于基本和高级执行计划理解的实用链接：
* http://www.simple-talk.com/sql/performance/execution-plan-basics/
* http://www.mssqltips.com/sqlservertip/1856/sql-server-query-execution-plans-in-sql-server-management-studio/

Actual和Esitmated执行计划之间的区别：
* http://blog.sqlauthority.com/2007/08/28/sql-server-actual-execution-plan-vs-estimated-execution-plan/

SQL Server产品价格并列

2 个答案: