SQL-按分組進行列更新

Question

我正在使用AdvantureWorks DB，但是SalesOrderDetail表上沒有“實際銷售”值。 該行應包含按訂單ID的LineTotal聚合。

我需要將這些值輸入到“實際銷售”列中的每個訂單ID行：

select SUM(LineTotal) as ActualSales
from Sales.SalesOrderDetail
group by SalesOrderID

Answer 1

您需要將要分組的字段添加到查詢中：

select SalesOrderID, sum(LineTotal) as ActualSales 
from SalesOrderDetail 
group by SalesOrderID

Answer 2

您可以使用JOIN進行UPDATE ，如下所示：

UPDATE od
SET od.ActualSalesColumn = g.ActualSales
FROM Sales.SalesOrderDetail od
INNER JOIN
(
    SELECT 
      SalesOrderDetail, 
      SUM(LineTotal) as ActualSales 
    FROM Sales.SalesOrderDetail 
    GROUP BY SalesOrderID
) g ON od.SalesOrderID = g.SalesOrderID;

或：使用CTE：

WITH ActualSales
AS
(
     SELECT 
       SalesOrderDetail, 
       SUM(LineTotal) as ActualSales 
     FROM Sales.SalesOrderDetail 
     GROUP BY SalesOrderID
)
UPDATE od
SET od.ActualSalesColumn = g.ActualSales
FROM Sales.SalesOrderDetail od
INNER JOIN ActualSales g ON od.SalesOrderID = g.SalesOrderID;

Answer 3

UPDATE x
SET x.ActualSales = x.NewActualSales
FROM (
      SELECT ActualSales, SUM(LineTotal) OVER (PARTITION BY SalesOrderID) AS NewActualSales
      FROM Sales.SalesOrderDetail
      ) x