Questions
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1How does MySQL handle updates to parent keys that are referenced by foreign keys?
2How does InnoDB enforce foreign key constraints internally?
3How can you find all foreign key relationships in a MySQL database?
4How do you drop a primary key or foreign key from an existing table?
5What are the differences between ON DELETE CASCADE and ON DELETE SET NULL? What is a super key, and how does it relate to candidate keys? Can a foreign key reference a non-primary key column in another table?
6What are candidate keys, and how do they differ from alternate keys?
7What is an AUTO_INCREMENT key, and how does it work with the primary key?
8What is a primary key? Can a table have more than one primary key?
9What is a key in MySQL and why is it used?
10How do foreign key constraints behave on DELETE and UPDATE operations (CASCADE, SET NULL, etc.)?
11Can you define a foreign key constraint referencing a table in a different database schema?
12Can a composite key contain a foreign key as one of its columns? Provide an example.
13Can two tables have the same primary key name? Explain.
14What is the impact of defining multiple UNIQUE keys on the same table?
15How do you define a primary key when creating a table?
16What is a foreign key and why is it important in relational databases?
17What is a composite key? How do you define one in MySQL?
18What happens if you try to insert a duplicate value into a UNIQUE key column?
19What is the difference between a UNIQUE key and a PRIMARY key?
20What are the differences between logical keys (like candidate or composite keys) and physical indexes?
21What are deferred constraint checks, and does MySQL support them? How do you design keys in a many-to-many relationship using a junction (bridge) table? What are the potential performance implications of using multiple foreign keys and composite keys in large-scale systems?
22How do you disable and re-enable foreign key checks in MySQL? Why would you do that?
23Can a primary key column contain NULL values? Why or why not?
24What is the difference between a key and an index?
25What is the purpose of the FOREIGN KEY constraint in maintaining referential integrity?
26Explain how key definitions affect indexing and query optimization.
