從3個表中總結數值

Question

我有3個表，每個表都會顯示用戶發佈消息的記錄。

我已經設法總結了每個用戶在每個表上發佈消息的次數，現在我想將這3個單獨的值彙總到每個用戶。

這是我迄今管理：

表USERMESSAGE：
SELECT U.SenderID, COUNT(U.SenderID) AS U_NUM FROM USERMESSAGE AS U WHERE U.SenderID != U.ReceiverID GROUP BY U.SenderID

表註釋：
SELECT C.UserID, COUNT(C.UserID) AS C_NUM FROM COMMENT AS C GROUP BY C.UserID

表好友列表：
SELECT F.UserID, COUNT(F.UserID) AS F_NUM FROM FRIENDLIST AS F WHERE F.ListName = 'News Feed' GROUP BY F.UserID

但並不是所有的用戶將在所有標籤中發帖所以某些用戶ID不會出現在某些表中。

Answer 1

我會嘗試這樣的事情

DECLARE @Table1 TABLE(
     UserID INT 
) 

DECLARE @Table2 TABLE(
     UserID INT 
) 

DECLARE @Table3 TABLE(
     UserID INT 
) 

INSERT INTO @Table1 (UserID) SELECT 1 
INSERT INTO @Table1 (UserID) SELECT 2 
INSERT INTO @Table1 (UserID) SELECT 3 

INSERT INTO @Table2 (UserID) SELECT 2 
INSERT INTO @Table2 (UserID) SELECT 3 

INSERT INTO @Table3 (UserID) SELECT 3 

SELECT ISNULL(CountTable1.CountUserIDTable1,0) + 
     ISNULL(CountTable2.CountUserIDTable2,0) + 
     ISNULL(CountTable3.CountUserIDTable3,0) CountOverTables, 
     UserIDs.UserID 
FROM (
      SELECT DISTINCT 
        UserID 
      FROM @Table1 
      UNION 
      SELECT DISTINCT 
        UserID 
      FROM @Table2 
      UNION 
      SELECT DISTINCT 
        UserID 
      FROM @Table3 
     ) UserIDs LEFT JOIN 
     (
      SELECT UserID, 
        COUNT(UserID) CountUserIDTable1 
      FROM @Table1 
      GROUP BY UserID 
     ) CountTable1 ON UserIDs.UserID = CountTable1.UserID LEFT JOIN 
     (
      SELECT UserID, 
        COUNT(UserID) CountUserIDTable2 
      FROM @Table2 
      GROUP BY UserID 
     ) CountTable2 ON UserIDs.UserID = CountTable2.UserID LEFT JOIN 
     (
      SELECT UserID, 
        COUNT(UserID) CountUserIDTable3 
      FROM @Table3 
      GROUP BY UserID 
     ) CountTable3 ON UserIDs.UserID = CountTable3.UserID 

Answer 2

SELECT用戶ID，SUM（NUM）爲總 FROM（SELECT AS U.SenderID用戶ID，COUNT（U.SenderID）AS NUM FROM USERMESSAGE爲u WHERE U.SenderID！= U.ReceiverID GROUP BY U.SenderID

UNION ALL 
SELECT C.UserID, COUNT(C.UserID) AS NUM FROM COMMENT AS C GROUP BY C.UserID 

UNION ALL 
SELECT F.UserID, COUNT(F.UserID) AS NUM FROM FRIENDLIST AS F WHERE F.ListName = 'News Feed' GROUP BY F.UserID 
) 
GROUP BY UserID