Create a subquery in a view SQL- ORACLE - sql

Question

I am setting up a database view.
I have a table PERSON and a RELATION_COMPANY related by the person_id. I amb trying to obtain the min date from the relation_company for each person_id.
I need to use a subquery?
This is what I have tried so far.
CREATE OR REPLACE VIEW PEOPLE_ADDRESS
select
p.id as ADDRESS_CODE,
case p.type_
when 1 then 'JURIDICAL'
when 0 then 'NATURAL'
end PERSON_TYPE,
(select min(start_date) from relation_company where relation_company.person_id = p.id) as INITIAL_dATE
P.ID as PERSON_CODE,
p.ADDRESS_NAME as ADDRESS,
p.POSTAL_CODE as POSTAL_CODE,
case P.COUNTRY_ID
when 68 then 'NO'
else 'YES'
end FOREIGN_INDICATOR
from
PERSON p join relation_company r on relation_company = p.id ;
That's my person table:
ID TYPE_ ADDRESS_NAME NAME OTHER COLUMNS
1 0 AVENUE SMITH, 19 MICHAEL SCOTT ....
2 1 OXFORD STREET , 119 COMPANY A ....
3 1 CHESTHAM ROAD, 7 COMPANY B ....
That's the RELATION_COMPANY table:
ID PERSON_ID START_DATE
1 1 2016-12-12 00:00:00
2 1 1981-07-09 00:00:00
3 2 1991-10-10 00:00:00
4 2 1981-03-09 00:00:00
5 3 1984-07-05 00:00:00
6 3 1981-08-11 00:00:00
7 3 1987-07-09 00:00:00
8 3 2011-07-09 00:00:00
select min(START_DATE) from RELATION_COMPANY group by PERSON_ID;
The result should be:
ADDRESS_CODE PERSON_TYPE INITIAL_dATE other columns
1 NATURAL 1981-07-09 00:00:00 ....
2 JURIDICAL 1981-03-09 00:00:00 ....
3 JURIDICAL 1981-08-11 00:00:00
I want to get the min(start_date) for each person_id and print it to the view to the column INITIAL_dATE.
I am having trouble to create that query.

Answer 1

You Already have the solution, this query are missing the "person_id" column in your SELECT statement.
Change this query
select min(START_DATE) from RELATION_COMPANY group by PERSON_ID;
To this.
select min(START_DATE),PERSON_ID from RELATION_COMPANY group by PERSON_ID;
Hope this helps.

Answer 2

You don't need a subquery for your solution.
Only add a group-clause to your query.
like this one:
select
p.id as PERSON_ID,
case p.type_
when '1' then 'JURIDICAL'
when '0' then 'NATURAL'
end PERSON_TYPE,
min(start_date) as INITIAL_dATE,
p.ADDRESS_NAME as ADDRESS,
p.POSTAL_CODE as POSTAL_CODE,
case P.COUNTRY_ID
when 68 then 'NO'
else 'YES'
end FOREIGN_INDICATOR
from PERSON p join relation_company r on r.person_id = p.id
group by p.id, type_, ADDRESS_NAME, POSTAL_CODE, P.COUNTRY_ID;