Het eindresultaat van wat je doet is dit:
select * from tableName where LOCATION_ID IN ('1,2,3');
En wat je nodig hebt is dit:
select * from tableName where LOCATION_ID IN (1,2,3);
Dus je kunt dit gebruiken:
select * from tableName where LOCATION_ID in (
select regexp_substr(P_LOCATIONS,'[^,]+{1}',1,level)
from dual connect by level <= length(regexp_replace(P_LOCATIONS,'[^,]*')) + 1
);