无法弄清楚如何根据同一个表中的一组列更新表中的列

Question

我正在尝试将列总数（Totl）更新为SUM（卷）除以COUNT（*），仅针对列/ s的组（周）中的行，在4个不同的表中水果（Fruit_Volume）和许多记录（有更多属性，如买家，种植区域..），我只想生成有机（Fruit_Type）的Apples（Item_Name）值，按周（日期）分组。 -TIA

UPDATE Fruit_Volume
SET Totl = B.Totl
FROM (SELECT SUM(Volume)/COUNT(*) Totl FROM Fruit_Volume
    WHERE Item_Name LIKE 'Apple%' AND Fruit_Type = 'Organic'
    GROUP BY Week -- I feel the need to group by Item_Group, Fruit_Type
     ) as B
WHERE Item_Name LIKE 'Apple%' AND Fruit_Type = 'Organic'

Answer 1

我假设你想在同一周内为同一产品记录多行的共同行，然后将其应用于受本周影响的水果。

UPDATE fv
SET fv.Totl = B.Totl
FROM 
    Fruit_Volume fv
    INNER JOIN
    (
        SELECT 
          SUM(Volume) / COUNT(*) Totl,
          [Week]
        FROM
          Fruit_Volume
        WHERE 
          Item_Name LIKE 'Apple%' AND Fruit_Type = 'Organic'
        GROUP BY 
          [Week]
     ) as B
     ON fv.[Week] = b.[Week]
WHERE 
    Item_Name LIKE 'Apple%' AND Fruit_Type = 'Organic';

SqlFiddle here

修改 通过CTE进行更新，查询可以DRY'd一点。

WITH cte AS 
(
  SELECT 
    *
  FROM
    Fruit_Volume
  WHERE 
    Item_Name LIKE 'Apple%' AND Fruit_Type = 'Organic'

)
UPDATE cte
    SET cte.Totl = B.Totl
    FROM 
        cte
        INNER JOIN
        (
            SELECT 
              SUM(Volume) / COUNT(*) Totl,
              [Week]
            FROM
              cte
            GROUP BY 
              [Week]
         ) as B
         ON cte.[Week] = b.[Week];

Updated fiddle