Okay I tried everything and wasted 3 complete days and everything went in vain.
No good.
The upgrade runs for few hours and then starts throwing resourceDB error and if we keep on changing the version numbes as it shows on core_resource, it goes ahead, but keeps on looping with all that kind of errors.
Till date, we have fixed every kind of error, we face with magento upgrade, except this resourceDB related problems.
Can anyone tell, whats the best method to handle this exact thing ?

resolved