带子表的SQL查询

Question

I have two tables Parent and Child.

Parent table has following columns

Parent_id, Name

Child Table has following columns

Parent_id (foreign key), Identifier, identifier_value

Now I want to list different parent_id with names and identifier_value(of child table) having same identifier_value for Identifier = "test" but different identifier_value for Identifier = "test1"

ie consider an example

Parent Table ---

Parent_id, Name
1, XYZ
2, PQR

Child Table

Parent_id, Identifier, Identifier_value
1, test, value1
1, test1, ghght 
2, test, value1
2, test1, khkhgj

output should be

1, XYZ, value1, ghght
2, PQR, value1, khkhgj

It should return result for the above example as in parent_id 1 and 2, test has same value but test1 has different value

This is what I have written till now

SELECT p.parent_id,
  p.name,
  eid.identifier_value,
  eid2.identifier_value
FROM parent p,
  child eid,
  child eid2
WHERE e.parent_id             = eid.parent_id
AND e.parent_id               = eid2.parent_id
AND eid.identifier  = 'test'
AND eid2.identifier = 'test1'
AND EXISTS
  (SELECT 1
  FROM child eid3
  WHERE eid3.identifier = 'test'
  AND eid3.value                    =eid.value
  AND eid3.parent_id             <> eid.parent_id
  AND EXISTS
    (SELECT 1
    FROM child eid4
    WHERE eid4.parent_id         = eid3.parent_id
    AND eid4.identifier = 'test1'
    AND eid3.value                 <> eid4.value
    AND eid4.identifier = eid3.identifier
    )
  )

The issue in the last subquery. Need some advice on it.

Answer 1

Is this what you are looking for?

select p.*, c1.Identifier_value, c2.Identifier_value
from parent p left join
     child c1
     on c1.parent_id = p.id and c1.identifier = 'test' left join
     child c2
     on c2.parent_id = p.id and c2.identifier = 'test2'
where c1.Identifier_value <> c2.Identifier_value;

Answer 2

What is the issue with the query given by gordon, Below are the results for the sample data which you have provided.

with parent_table as
(
select 1 as parent_id, 'XYZ' as name from dual
union
select 2 as parent_id, 'PQR' as name from dual
),
child_table as 
(
select 1 as parent_id, 'test' as Identifier, 'value1' as Identifier_value from dual
union
select 1 as parent_id, 'test1' as Identifier, 'ghght' as Identifier_value from dual
union
select 2 as parent_id, 'test' as Identifier, 'value1' as Identifier_value from dual
union
select 2 as parent_id, 'test1' as Identifier, 'khkhgj' as Identifier_value from dual
)
select p.*, c1.Identifier_value, c2.Identifier_value
from parent_table p left join
     child_table c1
     on c1.parent_id = p.parent_id and c1.identifier = 'test' left join
     child_table c2
     on c2.parent_id = p.parent_id and c2.identifier = 'test1'
where c1.Identifier_value <> c2.Identifier_value;

Output same as expected output in the question.

1   XYZ value1  ghght
2   PQR value1  khkhgj