Question

Hello I am trying to write a case statement that has a 1 year interval in this case the year starts at April and ends march of the following year, however If for example march of this year is entered then it would be the end of last year due to the fact that, the year would have started from last year April

Have a look at the sqlfiddle here

and this is the code that I have so far, note the

sum(case 
        when Month(py.pay_date) = 4 interval())1 year
        then amount end) yearly_amount

This is where I am having the major problem

Answer 1

You can use this for your yearly_amount calculation for the current year (starting in april and ending at the end of march in the next year):

sum(case 
        when py.pay_date >= STR_TO_DATE(CONCAT(YEAR(NOW()), '-04-01'), '%Y-%m-%d') and
             py.pay_date <  STR_TO_DATE(CONCAT(YEAR(NOW()), '-04-01'), '%Y-%m-%d') + interval 1 year
             then amount
        end) yearly_amount

SQLFiddle Demo