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PODatabase and class design
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  1. PODatabase and class design
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    copied!<p>Problem - I'm creating a group forum application for school and need to create design matching for following requirements.</p> <ul> <li>Many to many relationship between Group and Group Members.</li> <li>Group member can be either Student or Staff. (May be some other user roles as well in future).</li> <li>Already there exist Student and Staff tables in my database.</li> </ul> <p>Environment - Java, Spring, Hibernate, MySQL</p> <p>Approaches -</p> <p>1.a) DB design</p> <p>group : | id | name | is_active |</p> <p>group_member : | id | group_id | user_role | student_id | staff_id | is_banned | is_default_user |</p> <p>1.b) Class design (DTO classes)</p> <p>Group : GroupMember groupMembers[*], etc.</p> <p>GroupMember : UserRole userRole, Student student, Staff staff, etc.</p> <p>2.a) DB design</p> <p>group : | id | name | is_active |</p> <p>group_member : | id | group_id | is_banned | is_default_user |</p> <p>student_member : | id | group_member_id | student_id |</p> <p>staff_member : | id | group_member_id | staff_id |</p> <p>2.b) Class design</p> <p>Group : GroupMember groupMembers[*], etc.</p> <p>GroupMember : UserRole userRole, Member member, etc.</p> <p>interface Member : getMember():Object</p> <p>StudentMember extends Student implements Member : getMember():Student</p> <p>StaffMember extends Staff implements Member : getMember():Staff</p> <p>I prefer to 2nd approach. Seems it is more extendable. In 1st approach, always 1 column is null. It's waste.</p> <p>Is there any better approaches with mentioned environment (support for hibernate : I'm new bee) for this kind of matters ?</p>
 

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