If I understood your question correctly, you want to perform 2 queries that return 2 result sets that have the same fields. In your case, all you need is using the OR operator or the IN operator like this
select * from table_name where age=12 or age=13
select * from table_name where age IN (12, 13)
or you use the
UNION operator[
^] like this
select * from table_name where age=12
UNION
2 select * from table_name where age=13
The UNION operator is used to concatenate 2 result sets that have the same structure (same number of columns and similar data types in the same order). But in your case, the OR operator or the IN operator is enough.