Oracle 18c

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create table t_user(user_id number(10), company_id varchar2(20));
insert into t_user
select 123, 'company_id_1' from dual
union all
select 123, 'company_id_2' from dual;
2 rows affected

create table company(id varchar2(20), version_id varchar2(20));
insert into company
select 'company_id_1', null from dual
union all
select 'company_id_2', 'version_id1' from dual;
2 rows affected

select * from t_user;


USER_ID
COMPANY_ID


123
company_id_1

123
company_id_2


select * from company;


ID
VERSION_ID


company_id_1
null

company_id_2
version_id1


SELECT distinct(company_id)
FROM t_user
WHERE t_user.user_id = 123 
AND t_user.company_id IS NOT NULL
AND EXISTS
  (SELECT 1
  FROM company
  INNER JOIN t_user ON company.id = t_user.company_id AND company.version_id IS NOT NULL)


COMPANY_ID


company_id_1

company_id_2


SELECT 1
  FROM company
  INNER JOIN t_user ON company.id = t_user.company_id AND company.version_id IS NOT NULL


1


1


SELECT distinct(company_id)
FROM t_user
WHERE t_user.user_id = 123 
AND t_user.company_id IS NOT NULL
AND EXISTS
  (SELECT 1
  FROM company
  WHERE company.id = t_user.company_id AND company.version_id IS NOT NULL);


COMPANY_ID


company_id_2


SELECT 1
  FROM company
  WHERE company.id = t_user.company_id AND company.version_id IS NOT NULL;
ORA-00904: "T_USER"."COMPANY_ID": invalid identifier