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Ensuring data integrity
Posted by: Michael Reed
Date: July 30, 2010 09:45AM

I haven struggling on how to utilize the database schema to ensure that multiple sets of independent data never gets intertwined.

For instance, say I have bank accounts, members that belong to a given bank account (assume member can only belong to a single account), and transactions. I might do the following:

-accounts_id (PK)

-accounts_id (PK)
-members_id (PK)
-name, etc

-transctions_id (PK)
-accounts_id (FK references members.accounts_id)
-members_id (FK references members. members _id)

Members uses a composite primary key (members_id is unique for a given accounts_id), and Transactions references Members’s primary key.

I like this structure in that it ensures that a record can never be inserted into Transactions for a Account/Member combo that doesn’t exist.

What I do not like is that if I need a many-to-many relationship with Members, I have to add both accounts_id and members_id to the cross table. In addition to using more space, the larger concern is that the JOIN will require equality of both keys which might reduce speed. Also, I do not know if it is possible to use AUTO_INCREMENT on Members.members_id (I am using MySQL).

Any advice on how best to proceed. Thank you

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Ensuring data integrity
July 30, 2010 09:45AM
August 01, 2010 01:43PM

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