Here is a good article on how to add data validation on a form. Specifically, look at how two Submit buttons (greySubmit and blueSubmit) are placed on the screen - one that is hidden, and enabled only when the validation criteria is met, and the other one set to the opposite criteria.
You can also add additional text (e.g., red star) to indicate a field is mandatory in a Context Box. Add free form text (*) and change text color using the toolbar.
Thanks for your suggestions. I already gone through that articles and built my application.
But the question here is that "Can we restrict the user to enter after certain numbers/chars?" . For example a Employee ID field has 5 alphanumeric limit. Then, can we restrict the user to enter 6th character?