PowerCenter® provides a transformation language that includes SQL-like functions to transform source data. Use these functions to write expressions and create functions called user-defined functions.
User-defined functions reuse expression logic and build complex expressions. You can include them in other user-defined functions or in expressions. User-defined functions follow the same guidelines as expressions. They use the same syntax and can use the same transformation language components.
Expressions modify data or test whether data matches conditions. For example, you might use the AVG function to calculate the average salary of all the employees, or the SUM function to calculate the total sales for a specific branch.
You can create a simple expression that only contains a port, such as ORDERS, or a numeric literal, such as 10. You can also write complex expressions that include functions nested within functions, or combine different ports using the transformation language operators.