Question

我想找到最优化的方法从表中选择具有相同名称（如特定记录）的行。

ID  NAME
10  A
10  C
10  B
20  A
30  D
31  B

然后选择：

ID  NAME
20  A
31  B

我想到了这样的事情：

select * from table
where name in (select name from table where id = 10).

还有其他选择吗？

Answer 1

select name
from table
group by name
having count(*) > 1

Answer 2

我想你想要

select t.*
from t
where t.id <> 10 and
      t.name in (select t2.name from t t2 where t2.id = 10);

哦，基本上就是您的查询。您也可以这样做：

select t.*
from (select t.*,
             sum(case when id = 10 then 1 else 0 end) over (partition by name) as has_name_10
      from t
     ) t
where has_name_10 = 1 and id <> 10;

Answer 3

另一种方式：

with diff_name as (
select * from(
select 10 id , 'A' name from dual
union
select 10 id , 'B' name from dual
union
select 10 id , 'C' name from dual
union
select 20 id , 'A' name from dual
union
select 30 id , 'D' name from dual
union
select 31 id , 'B' name from dual))
select distinct b.* from diff_name a,
                diff_name b
where a.name=b.name
and a.id <>b.id
and a.id = 10

具有相同表的子查询

3 个答案: