SQL-组合不同数量值的列

我有3个表，其中有不同的数据。具体来说，每个表中每个mainID的值数量不同。我想做的是编写一个查询，从3个表中获取信息，并将其转换为底部的“最终表”

表1 表2 表3 最终表格

---

谢谢

您需要

左键加入
表2
和
表3
与
表1

像这样的东西应该对你有帮助

;WITH tab1
     AS (SELECT Row_number()OVER(partition BY [mainID] ORDER BY [value]) rn,*
         FROM   Table1),
     tab2
     AS (SELECT Row_number()OVER(partition BY [mainID] ORDER BY [value]) rn,*
         FROM   Table2),
     tab3
     AS (SELECT Row_number()OVER(partition BY [mainID] ORDER BY [value]) rn,*
         FROM   Table3)
SELECT a.mainID,
       a.value AS Table1Value,
       b.value AS Table2Value,
       c.value AS Table3Value
FROM   tab1 a
       LEFT JOIN tab2 b
              ON a.rn = b.rn
                 AND a.mainID = b.mainID
       LEFT JOIN tab3 c
              ON a.rn = c.rn
                 AND a.mainID = c.mainID 

注意：结果顺序没有列，因此结果顺序可能略有不同。如果您有任何列要排序结果，请将其添加到
行编号
窗口函数的
排序依据
左连接是您需要的，尽管您如何选择不将铅笔和奶昔与猫关联？你的逻辑或业务规则是什么？
mainID      value
------      ------
ID1         Pencil
ID2         Pencil

mainID      value
------      ------
ID1         Milkshake
ID1         Kool-Aid
ID2         Water
ID2         Soda

mainID      Table1Value       Table2Value        Table3Value
------      -----------       -----------        -----------
ID1         Dogs              Pencil             Milkshake
ID1         Cats                                 Kool-Aid
ID1         Elephant
ID1         Snake
ID1         Tiger
ID1         Lamb
ID2         Dogs              Pencil             Water
ID2         Cats                                 Soda
ID2         Elephant
ID2         Snake
ID2         Tiger

;WITH tab1
     AS (SELECT Row_number()OVER(partition BY [mainID] ORDER BY [value]) rn,*
         FROM   Table1),
     tab2
     AS (SELECT Row_number()OVER(partition BY [mainID] ORDER BY [value]) rn,*
         FROM   Table2),
     tab3
     AS (SELECT Row_number()OVER(partition BY [mainID] ORDER BY [value]) rn,*
         FROM   Table3)
SELECT a.mainID,
       a.value AS Table1Value,
       b.value AS Table2Value,
       c.value AS Table3Value
FROM   tab1 a
       LEFT JOIN tab2 b
              ON a.rn = b.rn
                 AND a.mainID = b.mainID
       LEFT JOIN tab3 c
              ON a.rn = c.rn
                 AND a.mainID = c.mainID