How To Use Logic Expressions
A logic expression is an expression that, when evaluated, yields either a $True or a $False result.
Logic expressions are subdivided into conditional expressions and Boolean expressions.
How To Construct Conditional Expressions
A conditional expression is a complex logic expression that consists of two value expressions and an associated conditional operator. The conditional operator performs a designated comparison of the value expressions and returns the result $True or $False. Conditional expressions can be combined into Boolean expressions.
The conditional operators are
<> (not equals)
< (less than)
> (greater than)
<= (less than or equals)
>= (greater than or equals)
Examples of Conditional Expressions
EmpNum < 1254
DeptNum >= EmpNum
First Name = “Smith”
DeptDesc <> “Sports”
EmpNum between 1000 and 2000
LastName like “%ith%”
Event.EventName in (“F1”, “F2”, “Escape”)
ProdCode not between 542 and 863
LastName not in (“Smith”, “Jones”)
FirstName not like “Sm%”
How To Use Boolean Expressions
A Boolean expression is a complex logic expression that consists of one or more conditional expressions and an associated Boolean operator. The Boolean operator performs a Boolean operation on the $True or $False values returned by the conditional expression(s) and returns the result $True or $False.
The Boolean operators are
Examples of Boolean Expressions
LastName = “Allan” or FirstName = “Allan”
DeptNum = “Sports” and Salary > 45000 and LastName = “Smith”
not Salary > 45000