framework/resources/Functional/limit0/functions/data/concat_function.sql

select 
        concat(o.c_varchar, o.c_varchar),
        concat(r.c_varchar, o.c_varchar),
        concat(o.c_varchar, r.c_varchar),
        concat(r.c_varchar, r.c_varchar)
from 
        optional_type_v as o,
        required_type_v as r
where
        o.c_date = r.c_date;