Validate entire column with condition

Question

I have a list that has a column which is an integer. Is it possible when selecting a number to validate if this number has already been chosen in the list.

For example

List

Title Order

Item1 1

Item2 2

I create a new list item, select '2' for the Order item, and SharePoint kicks back saying 'Please select an Order number which does not exist'

Answer 1

You can in the column settings on the list mark the field with "Enforce unique values", that way each entry must be unique!

More, and the above image: http://adicodes.com/column-validations-and-list-validations-in-sharepoint-2010/