Our web-application is something like - users can create groups(request for membership of a group also), ask questions, answer etc. It is still in the development stage. What I want to do is tightly couple some of the tables.
For example - Whenever a new member joins a group(i.e when that table is being updated) it should be checked whether he/she is a valid user or Whenever someone asks a question in a group, before inserting the question in the table, it should be checked whether that user is a a member of that group etc.
I cannot do these checks using foreign keys because, the group mmbers are store in this way
group_id members mygroup member1,member2,member3 group001 member2,member10,member2,..<br>
As you can see they are stored by seperating commas. So I cannot put the foreign key constraint.
I do not want to do these checks in each and every servlet. I would like to do them in the database itself on insertion. Please tell me how to proceed with this?