只選擇具有唯一字段的行

Question

什麼是SQL命令，用於檢查行中沒有重複字段的行。

例如：

A A A B B B不應該在結果表。

如A B C D E F

只有行即等給出的數據：

A A A B B B 

A B C D E F 

A A B G H Q 

應該返回A B C D E F

Answer 1

Select distinc *返回唯一行的字段不是唯一的值。 您應該將每列的值與其他值進行比較。 （假設列類型相同）。例如，對於一個4列的表格，你應該做的smoething像：

SELECT Col1, Col2, Col3, Col4 FROM MyTable WHERE 
    Col1 NOT IN (Col2,Col3,Col4) AND 
    Col2 NOT IN (Col3,Col4) AND 
    Col3 <> Col4 

Answer 2

SELECT DISTINCT * FROM tablename 

Answer 3

SELECT DISTINCT col FROM tabl

Answer 4

SELECT * FROM MYTABLE

WHERE mytable.col1！= mytable.col2！= mytable.col3 ...

Answer 5

有沒有簡單的命令來做到這一點。

似乎是一個不尋常的要求，並可能表明，如果所有列都可以互換，表格不是第一範式。

在Microsoft SQL Server

;With YourData AS 
(
select 'A' as C1, 'A' as C2, 'A' as C3, 'B' as C4, 'B' as C5, 'B' as C6 UNION ALL 
select 'A' as C1, 'B' as C2, 'C' as C3, 'D' as C4, 'E' as C5, 'F' as C6 
) 
SELECT * 
FROM YourData 
WHERE 1 = 
     (SELECT TOP 1 COUNT(*) AS Cnt 
     FROM  ( 
       SELECT C1 AS  C 
       UNION ALL 
       SELECT C2 
       UNION ALL 
       SELECT C3 
       UNION ALL 
       SELECT C4 
       UNION ALL 
       SELECT C5 
       UNION ALL 
       SELECT C6 
       ) D 
     GROUP BY C 
     ORDER BY Cnt DESC 
     )