How to update the existing records?

For example to change old emplId’s with new emplId’s

Create CSV file with two columns – one Old EmplId ans second new emplId

Write a job to – step 1) Read the CSV file

                           step 2) the job should look for old EmplId’s

                           step 3) once the EmplId found it should replace with new EmplId

All long the job should keep a count of number of employees read and number of employees updated