The new validation options with SharePoint 2010 will require some pretty nifty formulas. An example: supposing you have a form which looks up client details from an external database, but you also need to be able to enter a new client if it is not already in the list. In this case you need a form validation formula which checks to see that either one or other of the columns are not blank.

You can do this by using a Form Validation formula in SharePoint 2010 as follows:

  1. Create a column called Client which looks up data from an external database.
  2. Create a simple text column called New Client which will be used to enter a new client name, if the client does not already exist in the database.
  3. Use the following Form Validation formula to check that either the Client column or the New Client column has been filled out.

=OR(NOT([New Client]=0),NOT([Client]=0))