Question

如何将下面的表中的两行组合起来，以便在下面看到结果表？

ID     NAME      GROUP    OWNER
1      Shoes     Bulls    NULL
1      Shoes     NULL     Michael Jordan
2      Hat       NULL     NULL
2      Hat       NULL     Kobe Bryant
3      Boots     NULL     NULL
3      Boots     NULL     NULL

结果

ID     NAME      GROUP    OWNER
1      Shoes     Bulls    Michael Jordan
2      Hat       NULL     Kobe Bryant
3      Boots     NULL     NULL

Answer 1

SELECT ID, NAME, MAX(GROUP) AS GROUP, MAX(OWNER) AS OWNER
    FROM YourTable
    GROUP BY ID, NAME

Answer 2

使用GROUP BY和MAX：

SELECT
    ID,
    MAX(NAME) AS NAME,
    MAX(`GROUP`) AS `GROUP`,
    MAX(OWNER) AS OWNER
FROM yourtable
GROUP BY ID

Answer 3

对于显示的示例数据，这将起作用。

SELECT ID, NAME, MAX(GROUP) AS GROUP, MAX(OWNER) AS OWNER
FROM YourTable
GROUP BY ID, NAME

Answer 4

首先修复基表，以便通过缺少行（而不是null）对缺失的信息进行建模，提供一些查看的表以提供缺失数据的默认叙述，然后显示结果：

（标准SQL-99语法，在SQL Server 2008 R2上测试）

WITH Apparel  -- base table
     AS 
     (
      SELECT * 
        FROM (
              VALUES (1, 'Shoes'), 
                     (2, 'Hat'), 
                     (3, 'Test')
             ) AS T (apparel_ID, apparel_name)
     ), 
     ApparelGroups  -- base table
     AS 
     (
      SELECT * 
        FROM (
              VALUES (1, 'Bulls')
             ) AS T (apparel_ID, apparel_group_name)
     ), 
     ApparelOwners  -- base table
     AS 
     (
      SELECT * 
        FROM (
              VALUES (1, 'Michael Jordan'), 
                     (2, 'Kobe Bryant')
             ) AS T (apparel_ID, apparel_owner_name)
     ),
     ApparelGroupsNarratives  -- viewed table
     AS
     ( 
      SELECT apparel_ID, apparel_group_name AS apparel_group_narrative
        FROM ApparelGroups
      UNION
      SELECT apparel_ID, '(no group)' AS apparel_group_narrative
        FROM Apparel
       WHERE apparel_ID NOT IN (SELECT apparel_ID FROM ApparelGroups)
     ), 
     ApparelOwnersNarratives  -- viewed table
     AS
     ( 
      SELECT apparel_ID, apparel_owner_name AS apparel_owner_narrative
        FROM ApparelOwners
      UNION
      SELECT apparel_ID, '(no owner)' AS apparel_owner_narrative
        FROM Apparel
       WHERE apparel_ID NOT IN (SELECT apparel_ID FROM ApparelOwners)
     )
SELECT a.apparel_ID, a.apparel_name,
       g.apparel_group_narrative, n.apparel_owner_narrative  
  FROM Apparel a
       INNER JOIN ApparelGroupsNarratives g
          ON a.apparel_ID = g.apparel_ID
       INNER JOIN ApparelOwnersNarratives n
          ON a.apparel_ID = n.apparel_ID;

在一行中组合两行两个不同的列

4 个答案: