Expressions and operators
An expression is a combination of variables, constants, and operators, built up in accordance with certain rules. There are two main kinds of operators: unary and binary. All operators, except the negation operators, are binary. Expressions with unary operators have the general form:
operator operand
Expressions with binary operators have the following form, where each operand can be another expression, variable, or constant:
operand operator operand
The available operators can be divided into four categories: arithmetic, relational, logical, and control operators.
Arithmetic 

* / + 
\
& 
negation
multiply/divide/add/subtract
remainder after division
string concatenation 
Relational 
= or EQ
<> or NE
> or GT
< or LT
>= or GE
<= or LE 
is equal to
is not equal to
is greater than
is less than
is equal to or greater than
is equal to or less than 
Logical 
AND, OR, NOT 
logical 'and', 'or' and negation 
Control 
? : 
question mark expression 
The question mark expression is a special type of expression. The syntax is:
If the condition is TRUE, expr_1 is executed. If the condition is FALSE, expr_2 is executed. For example:
<condition> ? <expr_1> : <expr_2>
If the condition is TRUE, expr_1 is executed. If the condition is FALSE, expr_2 is executed. For example:
lng_1 = (a >= b) ? a : b
 if condition a >= b is TRUE lng_1 gets the value of a,
 else lng_1 gets the value of b.
For further information on the different operator types, see the following sections:
Related topics
