Execute the below query
select * from scpglobalconfig where category='MailFetching' and parameter='ProcessMails';
if there is no row available then execute below query alone.
insert into scpglobalconfig values('MailFetching', 'ProcessMails', '50');
if entry is there while executing the first query then update its value to 50 by executing below query
update scpglobalconfig set paramvalue = '50' where category='MailFetching' and parameter='ProcessMails';