假设表A中又三个字段a1,a2,a3
我想获取全部a1,a2,但想要每条记录的a2值不重复,
select a1, distinct a2 from A;报错
select distinct a1, a2 from A;会显示a1,a2不相同的项
请问如何获取想要的记录
我想获取全部a1,a2,但想要每条记录的a2值不重复,
select a1, distinct a2 from A;报错
select distinct a1, a2 from A;会显示a1,a2不相同的项
请问如何获取想要的记录
解决方案 »
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select * from
(select a1,a2 row_number() over(partition by a2,order by a2 desc) rn from a)
where rn = 1
select * from
(select a1,a2 row_number() over(partition by a2,order by a2 desc) rn from A)
where rn = 1
ORA-00923: 未找到要求的 FROM 关键字
select * from
(select a1,a2 , row_number() over(partition by a2,order by a2 desc) rn from A)
where rn = 1
a2 后面给个逗号
from table_name
group by a2这样可以不
(select a1,a2 , row_number() over(partition by a2 order by a1 desc) rn from A) A
where rn = 1
create table DUPL_TEST
(
NAME VARCHAR2(8), -- 相当于 a1
AGE INTEGER -- 相当于 a2
)insert into dupl_test (NAME, AGE)
values ('a', 25);insert into dupl_test (NAME, AGE)
values ('a', 26);insert into dupl_test (NAME, AGE)
values ('a', 25);insert into dupl_test (NAME, AGE)
values ('b', 25);insert into dupl_test (NAME, AGE)
values ('b', 27);insert into dupl_test (NAME, AGE)
values ('b', 25);insert into dupl_test (NAME, AGE)
values ('c', 25);insert into dupl_test (NAME, AGE)
values ('c', 25);insert into dupl_test (NAME, AGE)
values ('d', 25);insert into dupl_test (NAME, AGE)
values ('d', 25);commit;-- 暂时用max这个组函数来做了
select a.name, (select max(distinct age) from dupl_test b where a.name = b.name) age
from dupl_test a
group by name
还可以用 max函数来取的。select a2,max(a1)
from table_name
group by a2