Hi,
If you use LDB, it will process one by one pernr.
http://wiki.scn.sap.com/wiki/display/Snippets/Report+in+HR+ABAP+-+LDB
If you don't want to use, refer the below sample provided in the link by me.
http://wiki.scn.sap.com/wiki/display/Snippets/Report+in+HR+ABAP+-+without+LDB
If you know the list of pernr already, then you should loop for the above process.