The Expression Editor allows you to edit various Boolean or regular expressions in controls:
In this editor, you can type an expression manually, or select functions, operators and operands using the editor's controls.An expression is a string that, when parsed and processed, evaluates some value. Expressions consist of column/field names, constants, operators and functions. Column/field names must be wrapped with brackets. The following are examples of regular expressions:
"[Quantity] * [UnitPrice] * (1 - [BonusAmount])"
"[FirstName] + ' ' + [LastName]"
"[Country] == 'USA'"
"[OrderDate] > #8/16/1994# AND [Quantity] > 20"
The Expression Editor supports numerous standard functions, allowing you to easily perform different string, date-time, logical and math operations over data. You can access the available functions by selecting the Functions category.