Replace a column value with multiple values from another table - DB2

I have a complex query ((Q1 union Q2) intersect (Q3 union Q4)). Now the issue is one of the column involved in the queries has the value of 'Company'. This value can be a particular company name or a value of 'ALL' which means all companies. I have a separate company table which lists the company names. Now the logic is if one of the query in intersect has a value of 'ALL' and the other query is company 'C1', the result should return 'C1'. But currently since 'ALL' does not match 'C1' as a string value the intersect does not return anything. Is there anyway I can replace the 'ALL' row value with all the company names and then do the intersect? I want to do all the operations through SQL because handling it in code will be very cumbersome. I am using DashDB which is based on DB2.

Solution

This is the query that solved my issue (I have removed complexities from the query and only included those portions related to this question)

SELECT 
AA.OBJECT_TYPE, 
AA.OBJECT_FILTER_ID, 
CASE WHEN BB.OBJECT_FILTER_VALUE = 'ALL' 
  THEN AA.OBJECT_FILTER_VALUE 
  ELSE BB.OBJECT_FILTER_VALUE 
  END AS OBJECT_FILTER_VALUE FROM 
( 
    SELECT 
    OBJECT_TYPE, 
    OBJECT_FILTER_ID, 
    OBJECT_FILTER_VALUE 
    from COMPANY
) AS AA 
INNER JOIN 
( 
    SELECT 
    OBJECT_TYPE ,
    OBJECT_FILTER_ID ,
    OBJECT_FILTER_VALUE 
    FROM DETAILS
) AS BB 
ON 
AA.OBJECT_TYPE = BB.OBJECT_TYPE AND 
AA.OBJECT_FILTER_ID = BB.OBJECT_FILTER_ID AND
(
AA.OBJECT_FILTER_VALUE = BB.OBJECT_FILTER_VALUE OR 
AA.OBJECT_FILTER_VALUE = 'ALL' OR 
BB.OBJECT_FILTER_VALUE = 'ALL'
)