Question

我自己无法弄清楚这一点。希望有人能帮助我。

我有三个表：users，cards，referees和users_cards

用户：

id  |   userName  |   referee_id
----------------------------
1   |   u1        |    1
2   |   u2        |    1
3   |   u3        |    2

裁判员：

id  |   refName
--------------
1   |   ref1
2   |   ref2

牌：

id  |   cardName
--------------
1   |   card1
2   |   card2

Users_Cards：

user_id  |   card_id  |   color   |   number
-------------------------------------------
1        |   1        |   red     |   123
1        |   2        |   yellow  |   312
2        |   2        |   yellow  |   523
3        |   1        |   red     |   344

我想得到的结果是：

id   |   userName   |   refName   |   cards
1    |      u1      |    ref1     |   card1: red (123), card2: yellow (312)
2    |      u2      |    ref1     |   card2: yellow (523)
3    |      u3      |    ref2     |   card1: red (344)

等等......

当用户拥有多张卡时，我所能获得的只是多行。那么如何将它们组合起来呢。

感谢任何能帮助我的人！'

编辑：

目前我只使用LEFT JOIN s

SELECT UserName, refName cardName, color, number,
FROM users
LEFT JOIN referees ON users.referee_id = referees.id
LEFT JOIN users_cards ON users.id = users_cards.user_id
LEFT JOIN cards ON dbo.users_cards.card_id = cards.id

Answer 1

我认为没有简单的方法来格式化表的结果并将其附加到结果中。您可以尝试使用以下内容执行存储过程：

CREATE TABLE #temp
(
    user_id int,
    CardString nvarchar(50)
)

CREATE TABLE #userCards
(
    user_id int,
    CardsList nvarchar(50)
)

DECLARE @UserID int,
        @cardName nvarchar(50),
        @cardList nvarchar(250) 

INSERT INTO #temp
SELECT user_id, cardName + ': ' + color + ' (' + number + ')'
FROM User_Cards AS UC
INNER JOIN Cards AS C ON C.card_id = UC.card_id

WHILE EXISTS (SELECT * FROM #temp)
BEGIN
   SELECT TOP(1) @UserID = user_id FROM #temp

   SET @cardList = ''

   WHILE EXISTS (SELECT * FROM #temp WHERE user_id = @UserID)
   BEGIN
      SELECT TOP(1) @cardName = [CardString] FROM #temp WHERE user_id = @UserID
      IF @cardList <> ''
         SET @cardList = @cardList + ', '
      SET @cardList = @cardList + @cardName
   END

   INSERT INTO #userCards
   VALUES (user_id, @cardList)
END

SELECT users.id, users.userName, referees.refName, CardsList 
FROM users
LEFT JOIN referees ON users.referee_id = referees.id
LEFT JOIN #userCards ON #userCards.card_id = users.user_id

DROP TABLE #userCards
DROP TABLE #temp

这将返回您想要的内容。您还可以定义聚合函数（请参阅http://msdn.microsoft.com/en-us/library/ms190678.aspx）

Answer 2

SELECT users.id, UserName, refName,
 cards = (
    SELECT  
      STUFF(( 
           SELECT ', card' + CAST(ROW_NUMBER() OVER (ORDER BY cards.id) AS VARCHAR) 
                  +': '+ color + '(' + CAST(number AS VARCHAR) +')'
           FROM 
              users_cards
              LEFT JOIN cards ON dbo.users_cards.card_id = cards.id
           WHERE users.id = users_cards.user_id
           FOR XML PATH('')), 1, 1, '') 
  )
FROM users
LEFT JOIN referees ON users.refereeid = referees.id

在SQL Server中组合多行

2 个答案: