You can control how data is entered in a field in a table by choosing the appropriate data type and field size. You can also use properties, such as input masks and validation rules, to control how data is entered in a field.
Find out more about choosing an appropriate data type for a field
Set the field size for a Number or Text field
Require that data be entered in a field
Define an input mask to control data entry
Prevent duplicate entries in a field
Define a field validation rule
Define a record validation rule