Hi all,
i need help to build a select query or plpgsql-fucntion
for the following tables.
create table a (
id int,
name varchar(20)
)
create table b (
a_id int,
c_id int
)
create table c (
b_id int,
d_id int
)
create table d (
id int,
name varchar(20)
)
Is it possible to build a select query that selects d.name for each a.name where
a.id = b.a_id and d.id = c.d_id and each b.c_id must exist in c.b_id.
Example:
a: b: c : d:
id | name a_id | c_id b_id | d_id id | name
----|------- -------|----- -------|----- -----|--------
1 | A_Name1 1 | 1 1 | 1 1 | D_Name1
2 | A_Name2 1 | 2 2 | 1 2 | D_Name2
3 | A_Name3 2 | 1 3 | 2 3 | D_Name3
4 | A_Name4 3 | 3 4 | 2
3 | 4 5 | 3
4 | 5
i wish to have to following result:
--------|--------
A_Name1 | D_Name1
A_Name3 | D_Name2
A_Name4 | D_Name3
I hope someone could understand the problem
Thanks in advance and sorry for my bad english
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