i have a  object and fields are Year__c and Month__c, when user is trying to insert another record with the same year and same month. we need to throw an error

Hi Developers, i have one scenario to calculate Yearly average  based on the months.

Ex:
Monthly                              yearly                       results
january = 100  --->            (100)/1                       100
february= 200 --->            (100+200)/2                150
March =   300 --->             (100+200+300)/3        200
April    = 400--->                (100+200+300+400)/4...
------
-----
-----
December==1200          (100+200+300+400+... +1200)/12

Hi ,
My question is ,i have two fields in Visual fofrce page. at the time of loading the page the cursor will be displaying in fisrt field. i want to display the cursor in 2nd field .

how to solve this problem?

Hi Developers, i have one scenario to calculate Yearly average  based on the months.

Ex:
Monthly                              yearly                       results
january = 100  --->            (100)/1                       100
february= 200 --->            (100+200)/2                150
March =   300 --->             (100+200+300)/3        200
April    = 400--->                (100+200+300+400)/4...
------
-----
-----
December==1200          (100+200+300+400+... +1200)/12

Hi ,
My question is ,i have two fields in Visual fofrce page. at the time of loading the page the cursor will be displaying in fisrt field. i want to display the cursor in 2nd field .

how to solve this problem?