Validating text field
You will work with some controls that perform all checking automatically, requiring no code.
You will also create a custom validator with code that you write, which illustrates how you can add your own logic to the validation framework in the page.
You can use wildcard characters in your validation rules.
Validation text lets you provide a message to help users who input data that is not valid.
When data is entered, Access checks to see whether the input breaks a validation rule – if so, the input is not accepted, and Access displays a message.
When you define rules for tables, those rules apply when you import data.
To add validation rules to a table, you open the table and use commands on the Fields tab of the ribbon.