Question

SELECT
   C.SOId, Ser.TotalService, S.TotalSales 
FROM
  salesorder C
  INNER JOIN  (SELECT SOId,SUM(charge) as TotalService FROM sales_serviceline GROUP BY SOId)  Ser
  ON C.SOId = Ser.SOId
  INNER JOIN  (SELECT SOId,SUM(PriceEach*qty) as TotalSales FROM  salesline  GROUP BY  SOId)  S
  ON C.SOId = S.SOId

说明：一个SalesOrder有许多销售线一个SalesOrder有许多销售线服务

因此，如果销售订单具有saleslins＆amp; salesline_service然后上面的查询成功地检索了该销售订单的总金额，但是如果只有盐水线或仅销售线服务没有重试销售订单，如何更改此查询以获得所有结果？

Answer 1

我认为您正在寻找LEFT JOIN。如果Ser或S中没有行，那么LEFT JOIN将TotalService或TotalSales NULL

SELECT
   C.SOId, Ser.TotalService, S.TotalSales 
FROM
  salesorder C
  LEFT JOIN  (SELECT SOId,SUM(charge) as TotalService FROM sales_serviceline GROUP BY SOId)  Ser
  ON C.SOId = Ser.SOId
  LEFT JOIN  (SELECT SOId,SUM(PriceEach*qty) as TotalSales FROM  salesline  GROUP BY  SOId)  S
  ON C.SOId = S.SOId

如果您不想将它们设为NULL。然后您可以退出轻松使用COALESCE()。像这样：

SELECT
   C.SOId, 
   COALESCE(Ser.TotalService,0) AS TotalService, 
   COALESCE(S.TotalSales,0) AS TotalSales
FROM
  salesorder C
  LEFT JOIN  (SELECT SOId,SUM(charge) as TotalService FROM sales_serviceline GROUP BY SOId)  Ser
  ON C.SOId = Ser.SOId
  LEFT JOIN  (SELECT SOId,SUM(PriceEach*qty) as TotalSales FROM  salesline  GROUP BY  SOId)  S
  ON C.SOId = S.SOId

SQL Group By和;内部联接

1 个答案: