Select from multipe tables with no duplicate

Select from multipe tables with no duplicate

I have complex select statement from 5 tables, I want to avoid duplicates
rows that have same field value from one of the tables.
SELECT role_enname,lu_app_operations.operation_enname,
lu_applications.app_enname,
lu_app_oper_groups.oper_group_enname
FROM
app_operation_roles,roles,lu_app_operations,lu_applications,lu_app_oper_groups
WHERE app_operation_roles.role_id=roles.role_id
AND app_operation_roles.app_operation_id=lu_app_operations.app_operation_id
AND roles.app_id=lu_applications.app_id
AND lu_app_operations.app_oper_group_id=lu_app_oper_groups.app_oper_group_id
AND app_operation_roles.retired =0 AND roles.retired =0
In this query I don't to show duplicates rows based on
lu_app_operations.operation_enname