The solution is as follows: Create an Info Path form the way you usually would.
In Share Point, place an Info Path form web part into a web part page.
All standard controls ”except buttons ”have data validation features enabled.
An error message appears when you try to save or submit a data document that contains validation errors, as shown in Figure 8-1.
Most mistakes are typographical, but many errors result from missing, incomplete, or duplicate entries.
Validation during data entry has proven to be the best and easiest method of minimizing data errors and inconsistencies.
You use similar expressions as data validation rules, but data validation doesn t just highlight text box controls with bad or suspect data.