Expressions

Expressions are commonly used in the mapping command language in data transformation maps, validation maps, and functional acknowledgment maps.

The basic form of an expression is:

token operator token [ operator token [ operator token [...]]]

Where:

token - can be one of the following:

operator - is one of the following types of operators:

Quotation marks must be used at the start and end of a string constant. Either single (') or double quotes (") may be used, but whichever is used to start the string constant must also be used to end it.

Data Interchange Services client processes expressions from left to right following a set order of precedence. Precedence can be overridden with parentheses embedded within an expression.

All variables, constants, and simple elements have a specific data type. Data Interchange Services client converts the value to the appropriate data type for the expression. If it cannot convert the value to the appropriate type because the types are incompatible (for example, Boolean to binary), an error is issued during the control string compilation. If it cannot convert the data value to the appropriate type because the values are incompatible, (for example "xyz" to real), an error is issued during translation or a default value such as 0 is used.

Copyright IBM Corp. 2003, 2005