Convert SQL query to pivot - sql

Question

I can't seem able to get the logic to convert the following query to a pivot SQL. My table has 20 columns with roles on them, I'd like to convert those columns into rows so, when exported to Excel, I can filter on a single column since the values can be the same on the 20 columns. So far what I've done is convert the 20 columns into a single one and then split that single one into rows:
select distinct TASKID,
regexp_substr(t.roles,'[^|]+', 1, lines.column_value) as role
from (
select TASKID,
TRIM(ROLE1) || '|' ||
TRIM(ROLE2) || '|' ||
TRIM(ROLE3) || '|' ||
TRIM(ROLE4) || '|' ||
TRIM(ROLE5) || '|' ||
TRIM(ROLE6) || '|' ||
TRIM(ROLE7) || '|' ||
TRIM(ROLE8) || '|' ||
TRIM(ROLE9) || '|' ||
TRIM(ROLE10) || '|' ||
TRIM(ROLE11) || '|' ||
TRIM(ROLE12) || '|' ||
TRIM(ROLE13) || '|' ||
TRIM(ROLE14) || '|' ||
TRIM(ROLE15) || '|' ||
TRIM(ROLE16) || '|' ||
TRIM(ROLE17) || '|' ||
TRIM(ROLE18) || '|' ||
TRIM(ROLE19) || '|' ||
TRIM(ROLE20) as roles
from menu_roles
where RLTYPE='58'
) t,
TABLE(CAST(MULTISET(select LEVEL from dual connect by instr(t.roles, '|', 1, LEVEL - 1) > 0) as sys.odciNumberList)) lines
where regexp_substr(t.roles,'[^|]+', 1, lines.column_value) is not null
order by regexp_substr(t.roles,'[^|]+', 1, lines.column_value)
I'd understand that using PIVOT would be more efficient vs concatenating and splitting a string.
Thank you!

Answer 1

You appear to want UNPIVOT:
SELECT task_id,
role
FROM menu_roles
UNPIVOT ( role FOR role_number IN ( ROLE1, ROLE2, ROLE3, ROLE4 /*, ... */ ) );
Or, using UNION ALL:
SELECT task_id, role1 AS role FROM menu_roles
UNION ALL SELECT task_id, role2 AS role FROM menu_roles
UNION ALL SELECT task_id, role3 AS role FROM menu_roles
UNION ALL SELECT task_id, role4 AS role FROM menu_roles
-- ...