Synopsis: Keyless Entry
Understand the importance of foreign key constraints in maintaining referential integrity and preventing data inconsistencies. Learn how logical antipatterns like missing foreign keys lead to duplication and errors. This lesson helps you recognize problems in relational database design and offers practical solutions to simplify architecture and ensure data quality.
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The testing lab manager burst into my cubicle, “Bill, it looks like two managers have reserved the same server in our lab for the same days — how could this happen? Can you take a look into this and get it fixed? They’re screaming at me that they both need the equipment and that I’m holding up their project schedule.”
I designed an equipment-tracking application some years ago using MySQL. The default storage engine for MySQL was MyISAM, which doesn’t support foreign key constraints. The database had many logical relationships but could not enforce referential integrity.
As the project evolved and the application manipulated data in new ways, we developed a problem: when referential integrity wasn’t ...