dropdown box(sharepoint form field) validation sharepoint 2010

Question

I have a sharepoint form field(look up field), a dropdown box in a list...below is the screen shot when i type into it it finds the name..

but when i type a text which is not present in the drop down box it still accepts it

in firefox this dropdown box, does not allow to type in ..we are only using IE .. and our clients like the way that the drop down box allows u to type in to find the names...is there any way that i can incorporate a validation in it?

Answer 1

I think you should disable users to add unique values.

Go to your List > Settings > Column > Enforce Unique Values. See the screenshot below.

http://i.stack.imgur.com/6NkId.png