Dynamically I show the checkbox based on selected select box values.
By slecting checkboxes I will display the related values in a selectbox. While selecting a single checkbox, I can easily display related values into select box. While selecting more than one checkbox I want to display the related values in selectbox, without duplicates(repeatation).
How to do?
In one table I have fields Like , sub_assign_id,std_cat,std_id, sec_id, subject_id
In second table I have fields like,subject_id and subject.
I want to display the subject without repeatation in selectbox, if I click one or more than one check boxes

Show the code you have for retrieving your items.