SQL Query 用 JOINS 或其他东西替换 UNION ALL

Question

现在我有 3 张桌子

订单：

ID |日期 |机器 |规划

好作品：

ID |日期 |机器 |件 |产品

坏片：

ID |日期 |机器 |件 |产品 |组件

查询的输出是

日期 |机器 |规划 |好片|坏块

实际的查询是这样的：

SELECT
  data.Date AS Date,
  data.Machine AS Machine,
  SUM(CASE WHEN data.type = 'Planning' THEN data.value END ) AS Planning,
  SUM(CASE WHEN data.type = 'GoodPieces' THEN data.value END ) AS GoodPieces,
  SUM(CASE WHEN data.type = 'BadPieces' THEN data.value END ) AS BadPieces
FROM
      ( SELECT
          'Planning' AS Type,
          Date AS Date,
          Machine AS Machine,
          Planning AS Value
        FROM Orders
        UNION ALL
        SELECT
          'GoodPieces',
          Date,
          Machine,
          Pieces AS Value
        FROM GoodPieces
        UNION ALL
        SELECT
          'BadPieces'
          Date,
          Machine,
          Pieces AS Value
        FROM BadPieces ) AS data
GROUP BY
   Date,
   Machine

我的问题是有没有办法用这 3 个表获得相同的输出

订单：

ID |日期 |机器|规划

好作品：

订单ID |件 |产品

坏片：

订单ID |件 |产品 |组件

谢谢，

Answer 1

当然，只需在表格中添加LEFT JOIN 并对相应的列求和：

SELECT
  O.Date,
  O.Machine,
  SUM(COALESCE(O.Planning, 0)) AS Planning,
  SUM(COALESCE(G.Pieces, 0)) AS GoodPieces,
  SUM(COALESCE(B.Pieces, 0)) AS BadPieces
FROM
  Orders O
LEFT JOIN
  (SELECT G.OrderID,
     SUM(COALESCE(G.Pieces, 0)) AS GoodPieces
   FROM GoodPieces G
   GROUP BY G.OrderID) G ON G.OrderID = O.ID
LEFT JOIN
  (SELECT B.OrderID,
     SUM(COALESCE(B.Pieces, 0)) AS BadPieces
   FROM BadPieces B
   GROUP BY B.OrderID) B ON B.OrderID = O.ID
GROUP BY
  O.Date,
  O.Machine;

演示：http://www.sqlfiddle.com/#!3/09a73/17

编辑：更新为在 cmets 中由@MikaelEriksson 给出的句柄点。