SAP r/3 insert or update

Hi,

We have a scenario, in which we need to insert or update the data in the SAP r/3 based on the availability of the primary field in the SAP r/3.

For ex, if i have the employee details in SAP r/3 where in for a particular existing employee the salary details might be updated based upon the salary hike or if he is a new employee the details have to be inserted.

For this we have the primary field as the emp no.

How to proceed with this scenario.

Regards,

Kishore