Hello Karthikeyan,
you have to differentiate between ABAP on HANA and HANA native development.
From that what you wrote I assume that you are using an ABAP Netweaver Stack with HANA as database. As you wrote with that set up of course it is possible to write ABAP applications on the Netweaver stack, because that level is independent from the database using the database interface with a specific database specific library. With Netweaver 7.40 (and the following SPs 05, 08) several enhancements were introduced in ABAP and OpenSQL to benefit from the HANA capabilities in ABAP (e.g. enhanced OpenSQL to define more "complex" SQL statements to be able to push down work to the database; CDS; AMDPs). If you are interested in details I would recommend you to have a look to the openSAP course "ABAP Development for SAP HANA" (ABAP Development for SAP HANA - Dr. Jasmin Gruschke and Jens Weiler).
To come to your doubt regarding HANA. No, HANA is not just a database. HANA is a complete platform which allows you to write native HANA applications and to do a lot more things. On the HANA platform you cannot write ABAP coding, you implement native applications mainly with Serverside-JavaScript and SQLScript. For more information regarding the capabilities please have a look to the following sources:
- SAP HANA Developer Center
- HANA Developer Guide: http://help.sap.com/hana/SAP_HANA_Developer_Guide_for_SAP_HANA_Studio_en.pdf
- openSAP course Introduction to Software Development on SAP HANA (Repeat) - Thomas Jung
- openSAP course Next Steps in Software Development on SAP HANA - Thomas Jung and Rich Heilman
Best regards,
Florian