When you create an expression, you combine identifiers, values, and operators into a unit that produces a result. Expressions can be as simple as an arithmetic expression, such as (1 + 1), that produces a numeric result, 2. Or they can perform complex operations on data, such as the following validation expression which generates an error if the value of the Country field is France, Italy, or Spain and the PostalCode field contains fewer than or more than five characters:
= [Country] In ("France", "Italy", "Spain") And Len([PostalCode])<>5
You can create an expression using the Expression Builder, or you can create it on your own by combining the elements of the expression to do what you want.
Return to create an expression