How to use analytical functions inside a mapping

Question

Hello everybody. Here Isend you a trick that we are using for two years.
If you want to use a function (for instance :ROW_NUMBER() OVER (PARTITION BY ... ORDER BY ...)) inside a mapping you must create an expression with in the INGRP1 the fields you are going to use in the window function and in the OUTGRP1 the function you want. Create an Out -attribute with the expressión and link it to a distinct operator (using a "distinct" you encapsulte the sql and you will be able to use the function inside a filter - in the where clause.). The distinct can eliminate some register (depends on the function). If you validate the expression an error will appear (don't worry about that, the mapping will be ok).
But there is a limitation, you will not be able tou sum over, min over, max over (it detect that they are aggregator functions). Other limitation: the debugger doesn't run with this kind of functions.
Please publish this information on "The Warehouse Builder Utility Exchange". Mi email is [email protected] (if you need more information)

Answer 1

It is possible to add SUM, MIN, MAX functions also to OWB releases prior to Paris - You have to put them in double quotes - write "MIN" "MAX" "SUM" etc. The rest of the rules (adding cut-off operator after the expression - as DISTINCT, or UNION ALL) is analogical to with ROW_NUMBER()
That means You can create mapping with following functionality:
SELECT
sum (salary) over (partition by DEPARTMENT) department_salary,
salary,
employee_id,
employee_name
FROM employees_salaries
writing it this way in OWB:
SELECT
"SUM" (salary) over (partition by DEPARTMENT) department_salary,
salary,
employee_id,
employee_name
FROM employees_salaries
Regards,
Martin