Max Per

select m.mnf_code as mnfCode, m.mnf_name as mnfName, m.mnf_category as mnfCateg
				FROM  manufacturer as m,
									(
									select DISTINCT n.ngt_mnf_code as mnfCode FROM negotiation as n,  
												(
													select u.usr_email as mailUser
													FROM
													user as u
													WHERE u.usr_off_code='1' AND u.usr_type='B'
												) as usrByer
												WHERE usrByer.mailUser=n.ngt_buyer_usr_code
									) AS negManuf
				WHERE negManuf.mnfCode=m.mnf_code