title: Cascade Delete Query
body: <p>I have three tables.
  Product,  Company, Employee</p>
  
  <p>ProductId of Product table is foregin key for Company
  and CompanyId of Company table is foregin key for Employee</p>
  
  <p>So on deleting ProductId from Product table, all the related records in other tables should delete. But I can't touch schema(can't use alter table). How should I write the query in that case..</p>