我有一个包含类似这样的数据的表
TABLE_A
ID PARENT_ID NAME PROJECT_ID
1 abc
2 1 def
3 2 ghi
4 3 jkl 101
5 1 mno
我有另一个表,其中包含一些依赖于第一个表的项目' project_id' :
TABLE_B
ID PROJECT_ID NAME
1 101 prs
2 101 tuv
3 102 xyz
4 102 hgf
我想要一个像这样的结果;
abc
def
ghi
jkl
prs
tuv
mno
我尝试过这样的事情,但我不知道如何连接' TABLE_B'
SELECT LEVEL, A.NAME
FROM TABLE_A A
CONNECT BY PRIOR A.ID = PRIOR A.PARENT_ID
ORDER BY LEVEL;
答案 0 :(得分:2)
如果我理解你的需要,这可能是一种方式:
/* building a test case */
with TABLE_A(ID, PARENT_ID, NAME, PROJECT_ID) as (
select 1, null, 'abc', null from dual union all
select 2, 1 , 'def', null from dual union all
select 3, 2 , 'ghi', null from dual union all
select 4, 3 , 'jkl', 101 from dual union all
select 5, 1 , 'mno', null from dual
),TABLE_B(ID, PROJECT_ID, NAME) as (
select 1, 101, 'prs' from dual union all
select 2, 101, 'tuv' from dual union all
select 3, 102, 'xyz' from dual union all
select 4, 102, 'hgf' from dual
)
/* the query */
select name
from (
select ID, PARENT_ID, NAME, PROJECT_ID
from table_a
UNION ALL
select a.ID, a.PARENT_ID, b.NAME, a.PROJECT_ID
from table_b b
inner join table_a a
on a.project_id = b.project_id
)
start with parent_id is null
connect by prior id = parent_id
这里的想法是构建一个包含来自table_a
和table_b
的所有数据的部分结果,然后在分层查询中使用此结果,就好像它是一个表一样。
结果:
abc
def
ghi
jkl
prs
tuv
mno