Question

在这里，

有没有缩短这个MySQL查询？它需要根据它的价格规则从名为RuleValue的列中的PriceRuleDetail表中获取两个不同的行，但是使用别名，将它们返回到同一行。它在select语句中使用子查询，我认为是正确的，但可能有更简单的方法吗？

以下工作正常，我对此感到满意，但我想知道是否有办法让这个缩短???

SELECT Stock.*, 
    (SELECT PriceRuleDetail.RuleValue
    FROM PriceRuleDetail
    WHERE PriceRuleDetail.Sku = Stock.Sku
    AND PriceRuleDetail.PriceRule = 'RG'
    AND PriceRuleDetail.Quantity = 1) as Price,
    (SELECT PriceRuleDetail.RuleValue
    FROM PriceRuleDetail
    WHERE PriceRuleDetail.Sku = Stock.Sku
    AND PriceRuleDetail.PriceRule = 'RRP'
    AND PriceRuleDetail.Quantity = 1) as WasPrice
FROM Stock, StockCategoryMemberList
WHERE StockCategoryMemberList.Sku = Stock.Sku
AND StockCategoryMemberList.CategoryCode = 'FIRE'

提前致谢。

安迪

Answer 1

使用连接：

进行单个查询

SELECT
   Stock.*, 
   PRD1.RuleValue as Price, 
   PRD2.RuleValue as WasPrice
FROM 
   Stock, 
   StockCategoryMemberList, 
   PriceRuleDetail PRD1, 
   PriceRuleDetail PRD2
WHERE
StockCategoryMemberList.Sku = Stock.Sku
AND StockCategoryMemberList.CategoryCode = 'FIRE'
AND PRD1.Sku = Stock.Sku
    AND PRD1.PriceRule = 'RG'
    AND PRD1.Quantity = 1
AND
    PRD2.Sku = Stock.Sku
    AND PRD2.PriceRule = 'RRP'
    AND PRD2.Quantity = 1

我做了同样的假设（对于一个股票记录，只有一个价格，只有一个WasPrice）。如果不是这样的话......查询将无法正常进行。也不是你的。

Answer 2

您可以使用左连接来完成此操作

 SELECT Stock.*, 
        PRD1.RuleValue as Price, 
        PRD2.RuleValue as WasPrice
FROM 
   Stock INNER JOIN
   StockCategoryMemberList ON StockCategoryMemberList.Sku = Stock.Sku LEFT JOIN 
   PriceRuleDetail PRD1 ON PRD1.Sku = Stock.Sku
                        AND PRD1.PriceRule = 'RG'
                        AND PRD1.Quantity = 1 LEFT JOIN
   PriceRuleDetail PRD2 ON PRD2.Sku = Stock.Sku
                        AND PRD2.PriceRule = 'RRP'
                        AND PRD2.Quantity = 1
WHERE StockCategoryMemberList.CategoryCode = 'FIRE'

Answer 3

select s.*, prd1.rulevalue as price, prd2.rulevalue as wasprice
from
  stock s
  inner join stockcategorymemberlist scm
      on s.sku = scm.sku
  inner join priceruledetail prd1
      on prd1.sku = s.sku and prd1.pricerule='RG' and prd1.quantity=1
  inner join priceruledetail prd2
      on prd2.sku = s.sku and prd2.pricerule='RRP' and prd2.quantity=1
where
  s.categorycode='FIRE'

这也会更快，因为您不必为表中的每一行执行每个子选择。

Answer 4

我建议实际上加长它而不是使用Stock。*，但是使用每个列名。当你使用*时，它必须查询表以获取列名，并且慢一点。

如何缩短此MySQL查询？

4 个答案: