Question

以下是我需要完成的更好理解的粗略示例：

SampleTable

PrimaryKey SpecialCol1 RandomCol SpecialCol2
    1         aaa       sample1     111
    2         aaa       sample2     222
    3         bbb       sample3     444
    4         aaa       sample4     111
    5         ccc       sample5     444
    6         bbb       sample6     444

最终结果应如下所示：

PrimaryKey SpecialCol1 RandomCol SpecialCol2
--------------------------------------------
2         aaa       sample2     222
5         ccc       sample5     444

所以我只需要选择那些SpecialCol1和SpecialCol2组合在该表中唯一的行。我花了很多时间试图弄清楚它是如何完成的，但到目前为止还没有运气。

Answer 1

SELECT MIN(primarykey), specialcol1, MIN(randomcol), specialcol2 
FROM sampletable 
GROUP BY specialcol1, specialcol2 
HAVING COUNT(*) = 1;

Answer 2

分阶段进行。

查找列组合唯一的行：

SELECT SpecialCol1, SpecialCol2
  FROM SampleTable -- Thank you for invcluding the tablename
 GROUP BY SpecialCol1, SpecialCol2
HAVING COUNT(*) = 1;

查找匹配行的其他详细信息：

SELECT s.*
  FROM SampleTable AS s
  JOIN (SELECT SpecialCol1, SpecialCol2
          FROM SampleTable -- Thank you for invcluding the tablename
         GROUP BY SpecialCol1, SpecialCol2
        HAVING COUNT(*) = 1
       ) AS t
    ON t.SpecialCol1 = s.SpecialCol1 AND t.SpecialCol2 = s.SpecialCol2;

Answer 3

试试这个

  SELECT   PrimaryKey
            ,SpecialCol1
            ,RandomCol
            ,SpecialCol2  
    FROM (( SELECT   SpecialCol1+SpecialCol2 AS test
                    ,PrimaryKey
                    ,SpecialCol1
                    ,RandomCol
                    ,SpecialCol2  
            FROM table)) AS temp 
    WHERE test IN (SELECT test 
                    FROM ( SELECT SpecialCol1+SpecialCol2 AS test 
                           FROM table) AS temp 
                           GROUP BY test 
                           HAVING COUNT(test)=1 )

如何仅从表中选择那些行，其中两列不在该表中重复

3 个答案: