Guide

1. Open your database.

2. Go to the 'Navigation Pane' and right-click the table you want to modify. Select 'Design View'.

3. Click the field you want to set as NOT NULL.

4. In the 'Field Properties' section at the bottom, look for the 'Required' property.

5. Click the drop-down arrow and set the 'Required' property to 'Yes'.

6. Click the save icon to save your changes.