DataWindow Reference
DataWindow Operators and 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.

You use relational operators to compare a value with other values. The result is a boolean expression whose value is always true or false.  

Since the result of a boolean expression is always true or false, a relational operator that compares a value to null evaluates to false. For example, the expression "column > 5" evaluates to false (and "NOT column > 5" evaluates to true) when the column value is null.

When you write an expression, you can use the following relational operators (more information about LIKE, IN, and BETWEEN follows the table):

Special characters for operations with strings

You can use the following special characters with relational operators that take string values:

LIKE and NOT LIKE operators

Use LIKE to search for strings that match a predetermined pattern. Use NOT LIKE to search for strings that do not match a predetermined pattern. When you use LIKE or NOT LIKE, you can use the % or _ characters to match unknown characters in a pattern.

For example, the following expression for the Background.Color property of the Salary column displays salaries in red for employees with last names beginning with F and displays all other salaries in white:

If(emp_lname LIKE'F%',RGB(255,0,0),RGB(255,255,255))

Escape keyword

If you need to use the % or _ characters as part of the string, you can use the escape keyword to indicate that the character is part of the string. For example, the _ character in the following filter string is part of the string to be searched for, but is treated as a wildcard:

comment LIKE ~'%o_a15progress%~'

The escape keyword designates any character as an escape character (do not use a character that is part of the string you want to match). In the following example, the asterisk (*) character is inserted before the _ character and designated as an escape character, so that the _ character is treated as part of the string to be matched:

comment like ~'%o*_a15progress%~' escape ~'*~'

BETWEEN and NOT BETWEEN operators

Use BETWEEN to check if a value is within a range of values. Use NOT BETWEEN to check if a value is not in a range of values. The range of values includes the boundary values that specify the range.

For example, the following expression for the Background.Color property of the Salary column displays salaries in red when an employee's salary is between $50,000 and $100,000 and displays all other salaries in white:

If(salary BETWEEN 50000 AND 100000, RGB(255,0,0), RGB(255,255,255))

You can use the BETWEEN and NOT BETWEEN operators with string values. For example, if the following expression is used for the Visual property of a column, column values display only for departments listed alphabetically between Finance and Sales:

If(dept_name BETWEEN 'Finance' AND 'Sales',1,0)

The % or _ characters can be used when you are using string values with the BETWEEN and NOT BETWEEN operators. This example might include more department listings than the previous example:

If(dept_name BETWEEN 'F%' AND 'S%',1,0)

You can also use the BETWEEN and NOT BETWEEN operators with methods. For example:

GetRow( ) BETWEEN 5 AND 8

IN and NOT IN operators

Use IN to check if a value is in a set of values. Use NOT IN to check if a value is not in a set of values.

For example, the following expression for the Background.Color property of the Salary column displays salaries in red for employees in department 300 or 400 having a salary between $50,000 and $100,000, and displays all other salaries in white:

If(dept_id IN (300,400) and salary BETWEEN 50000 AND 100000, RGB(255,0,0), RGB(255,255,255))

City1=City2

Upper(City1)=Upper(City2)

City1=City2

Trim(City1)=Trim(City2)

City1 + ">" = City2 + ">"

You use logical operators to combine boolean expressions into a larger boolean expression. The result is always true or false:

When you combine two or more boolean expressions to form a new expression, the new expression is either true or false. The following truth table shows how true and false expressions are evaluated to form an expression that is either true or false.

For example, if "My dog has fleas" is true and "My hair is brown" is false, then "My dog has fleas OR my hair is brown" is true, and "My dog has fleas AND my hair is brown" is false:

If you use a logical operator with a boolean function that returns null, the term with the null return value is evaluated as false. If you use the NOT logical operator with a boolean function that returns null, the complete term evaluates to true. For example, NOT gf_boolean () evaluates to true when gf_boolean returns null.

The concatenation operator joins the contents of two variables of the same type to form a longer value. You can concatenate strings and blobs.

To concatenate values, you use the plus sign (+) operator.