Interview Guides
Key constraints are basic but important database concepts because they control how rows are identified and how tables relate to each other. In a QA setting, understanding them helps you reason about duplicate data, broken references, and schema validation.
You are asked to explain the difference between a primary key, a foreign key, and a unique key in a relational database. Describe what each constraint enforces, how they differ in purpose, and how they work together in a normalized schema. If helpful, use a simple example such as Telus Digital QA test runs and test cases.
The interviewer is looking for a clear conceptual explanation, not a long theory lecture. You should cover uniqueness, nullability, referential integrity, and whether a table can have one or multiple instances of each constraint type.
