在SQL Server上优化SQL查询

Question

我在SQL Server上有一个需要优化的SQL查询。 运行它需要将近16分钟。

SELECT DISTINCT DeptNo, 
       BrandDesc, 
       MfgDesc, 
       CountOfActiveSKUs = 
        COALESCE((SELECT COUNT(*) 
           FROM dbo.SKU k 
           WHERE k.Status = 'A' 
           AND k.BrandDesc = s.BrandDesc 
           AND k.MfgDesc = s.MfgDesc 
           AND k.DeptNo = s.DeptNo), 
          0) 
      FROM dbo.SKU s 
     ORDER BY BrandDesc 

我想出了以下内容，但它似乎并不抓住它有CountOfActiveSKUs = 0

SELECT DISTINCT DeptNo, 
       BrandDesc, 
       MfgDesc, 
       CountOfActiveSKUs = COALESCE(Count(*), 0) 
      FROM dbo.SKU 
      WHERE Status = 'A' 
     GROUP BY BrandDesc, MfgDesc, DeptNo 
     ORDER BY BrandDesc 

任何帮助表示赞赏记录， 谢谢！

Answer 1

我会写为：

SELECT DeptNo, BrandDesc, MfgDesc, 
     SUM(CASE WHEN status = 'A' THEN 1 ELSE 0 END) OVER (PARTITION BY BrandDesc, MfgDesc, DeptNo) as CountOfActiveSKUs 
FROM dbo.SKU s 
ORDER BY BrandDesc; 

我将离开SELECT DISTINCT出来，除非它是绝对必要的。如果有必要，则使用一个明确的GROUP BY：

SELECT DeptNo, BrandDesc, MfgDesc, 
     SUM(CASE WHEN status = 'A' THEN 1 ELSE 0 END) as CountOfActiveSKUs 
FROM dbo.SKU s 
GROUP BY DeptNo, BrandDesc, MfgDesc 
ORDER BY BrandDesc; 

Answer 2

不要过滤状态，用状态=“A”使用条件的总和计数的SKU。

SELECT DISTINCT DeptNo, 
       BrandDesc, 
       MfgDesc, 
       SUM(CASE WHEN status = 'A' THEN 1 ELSE 0 END) as CountOfActiveSKUs 
      FROM dbo.SKU 
     GROUP BY BrandDesc, MfgDesc, DeptNo 
     ORDER BY BrandDesc 

Answer 3

尝试此

SELECT s.DeptNo, s.BrandDesc, s.MfgDesc, count(k.Status) as CountOfActiveSKUs 
FROM dbo.SKU s LEFT OUTER JOIN 
dbo.SKU k ON 
k.Status = 'A' AND k.BrandDesc = s.BrandDesc 
AND k.MfgDesc = s.MfgDesc AND k.DeptNo = s.DeptNo 
GROUP BY s.DeptNo, s.BrandDesc, s.MfgDesc 
ORDER BY BrandDesc 

Answer 4

[1]首先，我会重新写从而原始查询：

SELECT DeptNo, BrandDesc,MfgDesc, SUM(IIF(s.Status = 'A', 0, 1)) AS Count_StatusA 
FROM dbo.SKU AS s 
GROUP BY s.DeptNo, s.BrandDesc, s.MfgDesc 
-- ORDER BY s.BrandDesc -- Uncomment this line only when necessary 

和

[2]然后，我会创建以下索引

CREATE /*UNIQUE*/ /*[NON]CLUSTERED*/ INDEX IUN_SKU_BrandDesc_DeptNo_MfgDesc 
ON dbo.SKU (BrandDesc, DeptNo, MfgDesc, Status) 

说明＃1：IIF（表达式，T，F）（SQL2012 +）可以与CASE代替WHEN EXPR则T ELSE六最终

注2：检查是否有重复/相似指数（上dbo.SKU表）

注意＃3：索引还应该包括de Status列。