After you've opened the table you want to change in Design view, click in the field for which you want to require an entry (in this example, the Product Name field).
In the property sheet, click in the Required field. A down arrow appears to the right of the field.
Click the down arrow and select Yes from the list that appears.
This field now requires an entry. Click the Save button on the Standard toolbar in the main Access window to save changes to the table.
For some fields, you may want to make sure that data is entered. For example, suppose that you have a product database table and that all products must have an ID. You can make the field that contains this value a required field so that the user is prompted to enter a value.
Handling Error Messages
Access lets you move out of the required field without typing an entry, but when you move out of the record containing the required field, you'll see an error message that names the required field. Click OK, complete the required field, and add the record.