Function for checking payments and arrears in DB needed

[dirman]

I need a function to manage payment by installment and when fee is fully paid

db.define_table('payment_type',

Field('category'),

Field('amount', 'double'),format='%(category)s %(amount)s')

db.define_table('fee',

Field('name', 'reference students'),

Field('category', 'reference payment_type'),

Field('payment_date', 'date'),

Field('arrears', 'double'),

Field('installment', 'double'))