I have two quantities Cat A , CatB
Now the items in Cat A can belong to many items in CatB. and CatB will also have many Items from Cat A.
I thinking of having Table1 for Cat A , Table2 for CatB and Table C for relation ship.
with
PK-A , PK-B
Is that correct.
How should i make my form in html so that user can select multiple values. Currently i am using select box
Any ideas?
Yes, in a relational database, a relationship table with foreign key into the two tables being related many-to-many is indeed the right way to go.
In HTML, use <select multiple="multiple"> for a multiple-selection select.
It would be best to ask these two separate questions as two separate questions, btw!-)
What you are telling can be cleared if you can show the columns in the tables. If you are saying "items" from CatA belongs to CatB and vice versa, it seems CatA and CatB supposed to be in a single table and the "items" should be in a different table. Please review your normalisation steps.