sql - T-SQL：将具有相等值的行“压缩”为一

Question

如果有任何行具有相同的值，是否有机会只显示一行？

我有以下情况：

身份证 | A栏| B栏| C栏

1 | 2 | '测试' | 5

2 | 3 | '测试'| 6

3 | 2 | '测试'| 5

在这种情况下，我只想显示以下结果集：

身份证 | A栏| B栏| C栏

1 | 2 | '测试' | 5

2 | 3 | '测试'| 6

谢谢你的帮助。

问候，亲

Answer 1

由于 id 列，您的行不是完全重复的。如果您不关心 id 的哪个值出现，您可以做您想做的事情：

select max(id) as id, ColumnA, ColumnB, ColumnC
from t
group by ColumnA, ColumnB, ColumnC

如果您根本不需要 id，这更简单：

select distinct ColumnA, ColumnB, ColumnC
from t

Answer 2

Try this :

With cte As
( Select  * , row_number() over (partition by ColumnA, ColumnB,ColumnC
 order by ID ) as myrownumber from myTable
)
Select * from cte where myrownumber=1

Answer 3

select id, column1,column2,colum3 from
(
    select *, row_number() over (partition by column1,column2,colum3 order by id) as sno 
    from table
) as t
where sno=1

Answer 4

CREATE TABLE #test
(
    ID      TINYINT     NOT NULL,
    colA    TINYINT     NOT NULL,
    colB    VARCHAR(10) NOT NULL,
    colC    TINYINT     NOT NULL
);

INSERT INTO #test VALUES (1,2, 'test', 5);
INSERT INTO #test VALUES (2,3, 'test', 6);
INSERT INTO #test VALUES (3,2, 'test', 5);

SELECT 
    ID,
    ColA,
    ColB,
    ColC
FROM 
(   
    SELECT 
        ID,
        ColA,
        ColB,
        ColC,
        ROW_NUMBER() OVER(PARTITION BY ColA ORDER BY ColA DESC) AS RowNum
      FROM #test
) AS WorkTable
WHERE RowNum = 1