In what format is this other application giving you data? Is the application writing directly to your database?
If you are handling the data before it gets entered into your database then I would seriously reconsider a redesign of the table format and of the way you are inserting data. There is no normalisation here, which is half the point of a database structure.
I don't see why the data cannot just be written into one row:
12 | A | B | C
Do you have a more meaningful example of the data you are using? What datatypes are you utilising?