Question

我在Access SQL语句上挣扎。我试着在这里找到一些答案，但似乎没有任何问题可以涵盖我的意思：

我需要通过某个标题对记录进行分组，然后在每个组中我只想选择1个（第一个）出现的部分，如：

Title | Part
--------------
one       A
one       A
one       B
one       B
one       C
one       C
-------------
two       A
two       A
two       B
two       B
two       C
two       C

Wished Result:

Title | Part
--------------
one       A
one       B
one       C
-------------
two       A
two       B
two       C

我对任何帮助感到高兴：）

到目前为止，我尝试了几种GROUP BY，ORDER BY，DISTINCT的组合，但没有任何结果导致结果。

Answer 1

SELECT title,part FROM t GROUP BY title,part

Answer 2

select distinct title, part from table

Answer 3

希望我能正确理解问题。

试图创造类似的情况。请查看以下查询。

Rextester Link - http://rextester.com/TNSME52397

create table test
(

    col1 varchar(100),
    col2 varchar(100)


    )


insert into test values('one','A');
insert into test values('one','A');
insert into test values('one','B');
insert into test values('one','B');
insert into test values('one','C');
insert into test values('one','C');
insert into test values('two','A');
insert into test values('two','A');
insert into test values('two','B');
insert into test values('two','B');
insert into test values('two','C');
insert into test values('two','C');


select col1 , col2 from
(
select col1 , col2 ,
row_number()over (partition by col1,col2 order by col1,col2) rn
from test
) a
where rn =1
;

Answer 4

create table test
(

    col1 varchar(100),
    col2 varchar(100)


    )


insert into test values('one','A');
insert into test values('one','A');
insert into test values('one','B');
insert into test values('one','B');
insert into test values('one','C');
insert into test values('one','C');
insert into test values('two','A');
insert into test values('two','A');
insert into test values('two','B');
insert into test values('two','B');
insert into test values('two','C');
insert into test values('two','C');


select unique col1 , col2,rn from
(
select col1 , col2 ,
dense_rank()over (partition by col1,col2 order by col1,col2) rn
from test
) a
where rn =1
;

Answer 5

SELECT * FROM (
SELECT col1,col2,
    RANK() over(partition by col1,col2
                ORDER BY ROWNUM) R
FROM test)
where R=1;


SELECT * FROM test
WHERE ROWID IN (
SELECT MIN(ROWID)
FROM test
GROUP BY col1,col2)
ORDER BY col1,col2;

SELECt * FROM test A
WHERE 1 = ( SELECT COUNT(1) 
            FROM test B 
            WHERE A.col1 = B.col1
            AND A.col2 = B.col2
            AND A.ROWID >= B.ROWID);
            
            
SELECT col1,col2
FROM test
UNION 
SELECT NULL,NULL
FROM DUAL WHERE 1=2;

Access SQL：如何在每个组中分组和选择不同的值？

5 个答案: