Merge Into ----using table to keep properties contents

CREATE TABLE properties_bvoip3 (identifier VARCHAR2 (4000), value VARCHAR2 (4000)) ;

merge into properties_bvoip3 p
using (select ‘one_key‘ identifier, ‘one_value‘ value from dual) s
on (p.identifier = s.identifier)
when matched then update set p.value = s.value
when not matched then insert (identifier,value) values (s.identifier, s.value);

create or replace function get_property_bvoip3( p_key Varchar2(4000)) return varchar2 as
l_tmp varchar2(4000);
begin
    select value into l_tmp from properties_bvoip3 where p_key=identifier;
    return l_tmp;
    exception when others then
        return null;
end;
/

l_value := get_property_bvoip3(‘one_key‘);