SQL最喜歡的顏色測驗

Question

下表假設：

USER COLOR ORDER 
================== 
JOE RED 1 
JOE BLUE 2 
PHIL BLUE 3 

喬首先選擇了紅色，則選擇了藍色作爲他最喜歡的顏色？你怎麼寫，返回的查詢：

COLOR COUNT 
RED 1 
BLUE 1 

只有喬的第一票纔算數？

Answer 1

你會得到每個用戶的最低階值，然後加入該對錶再由COLOR獲得這些記錄的顏色，然後組算來：

select y.COLOR, count(*) as COUNT 
from (select USER, min(ORDER) as ORDER from TheTable group by USER) x 
inner join TheTable y on x.USER = y.USER and x.ORDER = y.ORDER 
group by COLOR 

Answer 2

最難的部分是，大多數在表中的列是保留關鍵字...

CREATE TABLE #Votes (
    [USER] VARCHAR(50), 
    COLOR VARCHAR(50), 
    [ORDER] INT 
) 

INSERT INTO #Votes ([USER], COLOR, [ORDER]) VALUES ('JOE', 'RED', 1) 
INSERT INTO #Votes ([USER], COLOR, [ORDER]) VALUES ('JOE', 'BLUE', 2) 
INSERT INTO #Votes ([USER], COLOR, [ORDER]) VALUES ('PHIL', 'BLUE', 2) 

;WITH NumberedVotes AS (
    SELECT 
     [USER], 
     COLOR, 
     ROW_NUMBER() OVER (PARTITION BY [USER] ORDER BY [ORDER]) AS RowNumber 
    FROM #Votes 
) 
SELECT 
    COLOR, 
    COUNT(*) AS [COUNT] 
FROM NumberedVotes 
WHERE RowNumber = 1 
GROUP BY COLOR 
ORDER BY [COUNT] DESC 

Answer 3

這是基本相同的我的回答here，我在那裏提供更多的解釋，也是。

SELECT color,count(*) AS count 
FROM votes AS v 
JOIN (
    SELECT user,MIN(order) AS order 
    FROM votes 
    GROUP BY user 
) AS v2 ON (v.user=v2.user AND v.order=v2.order) 
GROUP BY color; 

Answer 4

declare @tb table ([user] varchar(10), color varchar(10), [order] int identity (1,1)) 

insert @tb ([user],color) 
select 'JOE' [user], 'RED' color 
union all 
select 'JOE' [user], 'BLUE' color 
union all 
select 'PHIL' [user], 'BLUE' color 


select color, count(user) from 
(
select distinct p.color,t.[user] from @tb t 
     cross apply (select top 1 color from @tb e where e.[user] = t.[user] order by [order]) p 
) u 
group by color 

Answer 5

2005年TSQL版本，以下內容：

SELECT color, COUNT(color) AS VOTES FROM 
(SELECT *, ROW_NUMBER() OVER (PARTITION BY [user] ORDER BY [order]) AS Row FROM @votes) T 
WHERE T.Row = 1 GROUP BY color