SQL - 加入2个查询？

Question

我有两个querys：

Select trunc(create_dtime) as Day, Count(Player_Id) as New_Users 
From Player 
Where Trunc(Create_Dtime) >= To_Date('2012-Jan-01','yyyy-mon-dd') 
Group By Trunc(Create_Dtime) 

每天

Select trunc(create_dtime) as Day,Count(Player_Id) as Retained_Users 
From Player 
Where Trunc(Create_Dtime) >= To_Date('2012-Jan-01','yyyy-mon-dd') 
And Trunc(Init_Dtime) >= Trunc(Sysdate) - 7 
Group By Trunc(Create_Dtime) 
Order By Day Asc 

具有价值，我想这两个查询连接在一起，所以我只有一个查询，而不是两个。

Answer 1

你不应该需要一个连接有：

SELECT 
    TRUNC(CREATE_DTIME) AS DAY, 
    COUNT(PLAYER_ID) AS NEW_USERS, 
    COUNT(CASE WHEN TRUNC(INIT_DTIME) >= TRUNC(SYSDATE) - 7 THEN PLAYER_ID ELSE NULL END)  AS RETAINED_USERS 
FROM PLAYER 
WHERE TRUNC(CREATE_DTIME) >= TO_DATE('2012-Jan-01','yyyy-mon-dd') 
GROUP BY TRUNC(CREATE_DTIME) 
ORDER BY 1 

Answer 2

这只是一个内部联接，除非您想要在其他查询中包含没有匹配的结果。否则，您只需使用：

SELECT * FROM query1 INNER JOIN query2 ON query1.Day=query2.Day 

我应该注意到这是MySQL的语法，我没有意识到您将它标记为Oracle。如果不相同，语法可能会相似，但我从未使用过Oracle。

Answer 3

我明白了，我只是忘记标签列。

Select one.Day, one.New_Users, two.Retained_Users 
From 
(
Select trunc(create_dtime) as Day, Count(Player_Id) as New_Users 
From Player 
Where Trunc(Create_Dtime) >= To_Date('2012-Jan-01','yyyy-mon-dd') 
Group By Trunc(Create_Dtime) 
) One 
Inner Join 
(
Select trunc(create_dtime) as Day,Count(Player_Id) as Retained_Users 
From Player 
Where Trunc(Create_Dtime) >= To_Date('2012-Jan-01','yyyy-mon-dd') 
And Trunc(Init_Dtime) >= Trunc(Sysdate) - 7 
Group By Trunc(Create_Dtime) 
Order By Day Asc 
) Two On One.Day=Two.Day 
Order By 1