Sql选择2个表

Question

第一张图片是我的MySQL查询结果。 我想得到第二张图片。 请帮忙。

这是我的MySQL查询：

SELECT * FROM
(
SELECT 
      PPUser.[UserID] AS'UserID',
      PPUser.[UserName] AS 'Name',
      NULL AS 'RO',
      NULL AS 'RO_UserID'
FROM [RF_ROTeacher]
LEFT JOIN PPUser ON RF_ROTeacher.UserID = PPUser.PUID
UNION ALL
SELECT 
      NULL AS 'UserID',
      NULL AS 'Name',
      PPUser.[UserID] AS 'RO',
      PPUser.[UserName] AS 'RO_UserID'
FROM [RF_ROTeacher]
LEFT JOIN PPUser ON RF_ROTeacher.ROID = PPUser.PUID
)A   

谢谢大家。

Answer 1

您不需要两个不同的查询。试试这个

SELECT p.[UserID]   AS'UserID',
       p.[UserName] AS'Name',
       f.[UserID]   AS 'RO',
       f.[UserName] AS 'RO_UserID'
FROM   [RF_ROTeacher]
       LEFT JOIN PPUser f
              ON RF_ROTeacher.ROID = f.PUID
       LEFT JOIN PPUser p
              ON RF_ROTeacher.UserID = p.PUID 

Answer 2

您也可以尝试此查询以获得所需的结果：

SELECT UserID,Name,RO,RO_UserID FROM
(SELECT 
      ROW_NUMBER() OVER (PARTITION BY PPUser) AS row1,
      PPUser.[UserID] AS 'UserID',
      PPUser.[UserName] AS 'Name'
FROM [RF_ROTeacher]) A 

LEFT JOIN

(SELECT 
      ROW_NUMBER() OVER (PARTITION BY PPUser) AS row2,
      PPUser.[UserID] AS 'RO',
      PPUser.[UserName] AS 'RO_UserID'
FROM [RF_ROTeacher])B
ON A.row1=B.row2