Library › Book 15 › Constraints -- The Database's Built-In Test Suite
Constraints -- The Database's Built-In Test Suite
8.1🔒Why Constraints Are Your Safety NetDatabase constraints are the database's built-in test suite. They enforce data integrity rules at the lowest level -- even if the…
8.2🔒Types of Constraints
8.3🔒Testing Primary Key Constraints
8.4🔒Testing Foreign Key ConstraintsForeign keys have different behaviors when the referenced row is deleted. You must test each:
8.5🔒Testing Unique ConstraintsPro Tip: For emails, you almost always want case-insensitive uniqueness. If your unique constraint is case-sensitive, users could create…
8.6🔒Testing NOT NULL Constraints
8.7🔒Testing CHECK Constraints
8.8🔒Testing Default Values
8.9🔒Discovering Existing ConstraintsBefore writing tests, discover what constraints already exist:
8.10🔒Practice Schema 8: Content Management
8.11🔒ExercisesBeginner:
8.12🔒Q&AResume phrasing- Developed comprehensive constraint test suites covering PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL, CHECK, and DEFAULT constraints across…
8.13🔒Q&ACover letter framingI treat database constraints as the application's last line of defense -- and I test them as rigorously as application code. My constraint…
8.14🔒Q&AInterview framing"I approach constraint testing by first discovering what constraints exist -- querying pg_constraint gives me the ground truth. Then I…
8.15🔒Q&AWhat not to say- "If the database has constraints, I do not need to test them." -- Constraints can be accidentally removed by migrations; testing verifies…
8.16🔒Q&AQuestion 1Prompt: You join a new team and discover that the orders table has no foreign key constraint on the user_id column -- it was supposed to…
8.17🔒Q&AQuestion 2Prompt: Your application allows users to register with email addresses, and the emails should be unique. However, users report they can…
8.18🔒Q&AQuestion 3Prompt: A developer adds a CHECK constraint CHECK (status IN ('pending','active','suspended')) to the users table. But the migration fails…
8.19🔒Q&AQuestion 4Prompt: Your team uses ON DELETE CASCADE on the line_items foreign key to orders, but ON DELETE RESTRICT on the orders foreign key to…