ques of ebix on second round..

1.what is primary key?
2.if tl table is there, which has 1,2,2,3,3,4,4,5 i need to print only non repartable value..
3.whatever i give input as date i need to print next month of first date (eg: give input as 3 -MAY-2009 the output shout next of first date
4.the function which has two input parametet and should return total count of values( eg if i give 'karthick','k') i need to print total count of k..