In MS Access, there are 2 very usefull properties that DB
Designer can use to provide restriction to value entered
by user in a certain field.
MS Access 97 or above MS SQL Server 2000
1. Validation Rule - Constraint
2. Validation Text - - (none)
Suppose that I have table name TUser contain field
name "Credit". What DB Designer want to is value entered
in this field must be greater than 1. If user enter value
out of range, User must receive a certain text in order to
inform what go wrong with value they have just entered.