WHERE

Controls the evaluation of other expressions.

expression1 WHERE expression2

expression1	A value expression.
expression2	A logic expression using conditional and Boolean operators.

If expression2 is logically true, the value of expression1; otherwise, $Null.

let i = { 1 where Age < 10,
2 where Age between 10 and 30,
4 where Age > 50, 3 }

Assigns a value to the variable i based on Age.

compute Employees evaluate
(let TotSal = $total(Salary where LastName = “Smith”)

Finds the total of the salaries of all employees named Smith.