sqlquery

Question

  i have 3 tables 1st contains regno,studname,classid,parent,address- named registration .
2nd contains classid,classname,fees etc named class.  
3rd  contains feeid,regid,classid,feedate,total -named fee.

i want to select at tne end of month  list of student whose are not paid the fee.
  select  regno,studname,classname,parent,address  from both registration and class whose are not paid the fee in the corresponding date?
 plz help.