mysql - 从 mySQL 5.5 到 SQL Server 2005 的语法更改

Question

我用 mySQL 5.5 版本编写了以下代码。

SELECT ss.ParcelID,ss.ParcelName,sh.Qty1,ShapeID1, sh.Qty2,sh.ShapeID2, sh.Qty3, sh.ShapeID3, sh.Qty4,sh.ShapeID4,
       MAX(case when ShapeID = 'EM' then Cng_InQty end) as EM_Qty,
       MAX(case when ShapeID = 'EM' then Cng_InWeight end) as EM_Weight,
       MAX(case when ShapeID = 'PR' then Cng_InQty end) as PR_Qty,
       MAX(case when ShapeID = 'PR' then Cng_InWeight end) as PR_Weight,
       MAX(case when ShapeID = 'AS' then Cng_InQty end) as AS_Qty,
       MAX(case when ShapeID = 'AS' then Cng_InWeight end) as AS_Weight
FROM sql_history ss
join sql_stock sh
WHERE ss.ParcelID = sh.ParcelID
GROUP BY ss.ParcelID;

我需要在 SQL Server 2005 中执行相同的查询，但我无法使用正确的语法编写查询。

Answer 1

在 SQL Server 中，如果不使用聚合函数，则无法在 SELECT 语句中使用不在 GROUP BY 中的列。要么使用聚合函数，要么将其添加到GROUP BY:

SELECT 
  ss.ParcelID,
  ss.ParcelName,
  sh.Qty1,
  ShapeID1, 
  sh.Qty2,
  sh.ShapeID2, 
  sh.Qty3, 
  sh.ShapeID3, 
  sh.Qty4,
  sh.ShapeID4,
  MAX(case when ShapeID = 'EM' then Cng_InQty end) as EM_Qty,
  MAX(case when ShapeID = 'EM' then Cng_InWeight end) as EM_Weight,
  MAX(case when ShapeID = 'PR' then Cng_InQty end) as PR_Qty,
  MAX(case when ShapeID = 'PR' then Cng_InWeight end) as PR_Weight,
  MAX(case when ShapeID = 'AS' then Cng_InQty end) as AS_Qty,
  MAX(case when ShapeID = 'AS' then Cng_InWeight end) as AS_Weight
FROM sql_history ss
join sql_stock sh ON ss.ParcelID = sh.ParcelID
GROUP BY ss.ParcelID,
  ss.ParcelName,
  sh.Qty1,
  ShapeID1, 
  sh.Qty2,
  sh.ShapeID2, 
  sh.Qty3, 
  sh.ShapeID3, 
  sh.Qty4,
  sh.ShapeID4;

然而，Mysql 允许在这种情况下为这些列选择任意值。