What you can put in a validation rule
Microsoft Access
Your validation rules can contain expressions — functions that return a single value. You can use an expression to perform calculations, manipulate characters, or test data. A validation rule expression tests data. For example, an expression can check for one of a series of values, such as "Tokyo" Or "Moscow" Or "Paris" Or "Helsinki". Expressions can also perform mathematical operations. For example, the expression <100 forces users to enter values that are less than 100. The expression ([OrderDate] - [ShipDate]) calculates the number of days that elapsed between the time an order was placed and the time it shipped.
For more information about expressions, see the article Create an expression.
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