I have a list box . I want that when submit is clicked then all the items added into the database except those which present in the database previously . All the items have productid and adminid which enters with them .
For example , i have product 1,2,3,4 for admin 1 and product 3 is already present in table for admin 1 then product 1,2,4 will be added and 3 will not as it is already added for admin 1 .