Calculate installment date

really thanks for ur support @sundar,actually i am the beginer, i will try to do,if u send me code mean i will happy sundar pls 

I will let you the logic, then if u cannot I will code it. 

 

1) First store the current  installement date in a variable. then add 30 days from this. store that day into Database. Select that stored Date and compare with Current Date. If both Matches then, Generate New Installement Date. Then Store that Date into Database. 

 

Its simple logic i shared. Please try. If you could not the i will code.