New value only if exists and has changed (slowly changing dimensions))

[Meg00]

Hi! I have a salary.qvd file that is filled with new data every month:

SalaryPeriod	EmpID	SalaryType	SalaryDescr	Amount
1901	1	01	Montly	30000
1901	1	02	Sick Leave	-800
1901	2	01	Monthly	38000
1901	2	011	Overtime	1500
1901	3	07	Hourly	32000
1901	3	011	Overtime	1000
1902	1	01	Monthly	30000
1902	1	011	Overtime Hourly	800
1902	2	01	Monthly	38000
1902	2	011	Overtime Hourly	1400
1902	3	07	Hourly	32000

The description of the salary type code might change over time. In the example above,  code 011 has changed from "Overtime" to "Overtime Hourly".

I want the end user app to always show the latest description for each code. 

My initial thought is to separate the description from the salary table and use mapping load and apply map, but I'm not sure how to solve to only chande description if it has changed.

Any suggestions?:)

[CELAMBARASAN]

I have made a script for you, Firstsortedvalue and separating the Salary desc from the main will make the original table undisturbed. Use the description from SalaryDesc table

Salary:
LOAD SalaryPeriod,
EmpID,
SalaryType,
SalaryDescr as [Original SalaryDescr],
Amount
FROM
[Salary.qvd]
(qvd);

SalaryDesc:
Load SalaryType, FirstSortedValue(DISTINCT [Original SalaryDescr], -1 * SalaryPeriod) as SalaryDescr
Resident Salary
Group by SalaryType;

thanks

Celambarasan