DataWindow Reference
Operators used in DataWindow expressions

When you write an expression, you can use the following arithmetic operators:

Multiplication and division

Multiplication and division are carried out to full precision (16-18 digits). Values are rounded:

Calculations with null

When you form an arithmetic expression that contains a null value, the expression becomes null. Thinking of null as undefined makes this easier to understand. For example, when a null column is multiplied by 5, the entire expression also evaluates to null. Use the IsNull function to explicitly check for the null value.

Boolean expressions that contain a null value evaluate to false rather than to null. For more information, see Relational operators in DataWindow expressions.