Some data is more important than other data. For example, a salesperson might need to know a contact’s phone number, but not necessarily the contact’s address. You can tell Access to prevent someone from moving beyond a required field without entering a value. For text and memo fields, you can require users to enter at least one character of text.
Open a table in Design view.
Click the field for which you want to require data entry.
Click in the Required property box.
Click the down ...