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表 mytable
a_id p_id
1 2
1 3
2 1
3 1
4 1
1 4
5 2
我想找出每一个p_id对应的所有的a_id数据,然后我想取到一个合并的结果集
p_id 为1的a_id 有三个 2 3 4
p_id 为2的有两个 1 5
p_id为3的有一个1
p_id 为4的有一个1
这种表有办法完成么?谢谢。
测试数据:
select * from a;
ID SNAME
---------- --------------------------------------------------
2 yang
4 Riddd
2 ff
4 Hlia
4 Yreer
SYS_CONNECT_BY_PATH
适用范围:8i,9i,10g及以后版本
SELECT t.id id, MAX(substr(sys_connect_by_path(t.sname, ','), 2)) str
FROM (SELECT id, sname, row_number() over(PARTITION BY id ORDER BY sname) rn
FROM a) t
START WITH rn = 1
CONNECT BY rn = PRIOR rn + 1
AND id = PRIOR id
GROUP BY t.id;
--10g用
select p_id,wm_concat(a_id) result from table group by p_id;
--9i,10g可用
with mytable as(
select 1 a_id,2 p_id from dual union all
select 1 a_id,3 p_id from dual union all
select 2 a_id,1 p_id from dual union all
select 3 a_id,1 p_id from dual union all
select 4 a_id,1 p_id from dual union all
select 1 a_id,4 p_id from dual union all
select 5 a_id,2 p_id from dual)
SELECT a.p_id, ltrim(MAX(sys_connect_by_path(a_id, ',')), ',') a_id
FROM (SELECT row_number() over(PARTITION BY t.p_id ORDER BY t.p_id) rn, t.* FROM mytable t) a
START WITH rn = 1
CONNECT BY PRIOR rn = rn - 1 AND
a.p_id = PRIOR a.p_id
GROUP BY p_id
ORDER BY p_id;
select a_id,replace(wm_concat(a_id),',','') result from table;
--不知是否要这个
select a_id,p_id from mytable where p_id in (1,2,3,4);