T-SQL結合多個列數分爲單列

Question

我有這個T-SQL（簡體）：

select 3.00 as score1, null as score2, null as score3, null as score4 
union all 
select null as score1, 4.5 as score2, 1.5 as score3, null as score4 

這主要生產：

score1 score2 score3 score4 
------------------------------ 
3.00 NULL NULL NULL 
NULL 4.5  1.5  NULL 

，但我想它加入到一行，像這樣：

score1 score2 score3 score4 
------------------------------ 
3.00 4.5  1.5  NULL 

對不起 - 即時繪圖空白（這是晚了一天）。

我需要臨時表嗎？

原因我做這是我有以下的關聯：

評論1 .. *成績

所以常規連接產生1行中每個分數 - 但我想插入一條記錄（到另一臺），有每個記錄的列 - 如果你知道我的意思：

INSERT INTO OtherTable (ReviewId, Score1, Score2, Score3, Score4) 
???? 

希望是有道理的。

編輯

基於@OMG小馬的回答（這是他剛刪除），我想出了這個：

SELECT CASE MAX(x.score1) WHEN 0 THEN NULL ELSE MAX(x.score1) END AS score4 
     CASE MAX(x.score2) WHEN 0 THEN NULL ELSE MAX(x.score2) END AS score4 
     CASE MAX(x.score3) WHEN 0 THEN NULL ELSE MAX(x.score3) END AS score4 
     CASE MAX(x.score4) WHEN 0 THEN NULL ELSE MAX(x.score4) END AS score4 
    FROM (select 3.00 as score1, 0 as score2, 0 as score3, 0 as score4 
     union all 
     select 0 as score1, 4.5 as score2, 1.5 as score3, 0 as score4) x 

但是它是相當難看。任何其他想法？

Answer 1

結束了我原來的查詢會（感謝@OMG爲小馬把我在正確的軌道上）：

SELECT CASE MAX(x.score1) WHEN 0 THEN NULL ELSE MAX(x.score1) END AS score4 
     CASE MAX(x.score2) WHEN 0 THEN NULL ELSE MAX(x.score2) END AS score4 
     CASE MAX(x.score3) WHEN 0 THEN NULL ELSE MAX(x.score3) END AS score4 
     CASE MAX(x.score4) WHEN 0 THEN NULL ELSE MAX(x.score4) END AS score4 
    FROM (select 3.00 as score1, 0 as score2, 0 as score3, 0 as score4 
     union all 
     select 0 as score1, 4.5 as score2, 1.5 as score3, 0 as score4) x 

Answer 2

在假定兩行中只有一行在score1，score2中有值的情況下，否則使用NULLIF函數重寫您的查詢。

SELECT 
    NULLIF(ISNULL(NULLIF(x.score1, 0), y.score1), 0) score1, 
    NULLIF(ISNULL(NULLIF(x.score2, 0), y.score2), 0) score2, 
    NULLIF(ISNULL(NULLIF(x.score3, 0), y.score3), 0) score3, 
    NULLIF(ISNULL(NULLIF(x.score4, 0), y.score4), 0) score4 
FROM (SELECT 3.00 AS score1, 0 AS score2, 0 AS score3, 0 AS score4) x 
CROSS JOIN (SELECT 0 AS score1, 4.5 AS score2, 1.5 AS score3, 0 AS score4) y 

Answer 3

當我嘗試它（SQL 2008）用一個簡單的MAX()似乎工作：

SELECT 
    MAX(score1), 
    MAX(score2), 
    MAX(score3), 
    MAX(score4) 
FROM 
    (select 3.00 as score1, null as score2, null as score3, null as score4 
    union all 
    select null as score1, 4.5 as score2, 1.5 as score3, null as score4) s 

我跑這個測試

declare @t table (i int null) 
insert @t values (null) 
insert @t values (1) 
select MAX(i) from @t 

這是你想要做什麼？

Answer 4

的@OMG小馬/ RPM1984查詢似乎工作：

SELECT MAX(x.score1), 
     MAX(x.score2), 
     MAX(x.score3), 
     MAX(x.score4) 
    FROM (select 3.00 as score1, null as score2, null as score3, CAST(null as int) as score4 
     union all 
     select null as score1, 4.5 as score2, 1.5 as score3, null as score4) x 

導致：

3.00 4.5 1.5 NULL 

我不知道，如果多行定義了相同的分數，你會怎麼做。

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我不得不CAST（null作爲INT）添加到第四列，否則沒有辦法爲SQL Server摸出第四列的類型 - 所有它有兩個空值，和空白可是任何類型的。