Database systems

ACID represents the fundamental properties—Atomicity, Consistency, Isolation, and Durability—that guarantee database transactions are processed reliably. Option C is incorrect because 'Concurrency' is a mechanism managed by isolation, not a core ACID property itself, and the 'D' stands for Durability rather than Data.

Second Normal Form (2NF) requires a relation to be in 1NF and ensures that all non-prime attributes are fully functionally dependent on the primary key, thereby eliminating partial dependencies. Third Normal Form (3NF) goes further by removing transitive dependencies, which are already absent of partial dependencies.

Second Normal Form (2NF) requires a relation to be in 1NF and ensures that all non-prime attributes are fully functionally dependent on the primary key, thereby eliminating partial dependencies. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !The WHERE clause filters rows before grouping, so using it to filter groups is a common mistake that leads to wrong results.
• !Option C is incorrect because 'Concurrency' is a mechanism managed by isolation, not a core ACID property itself, and the 'D' stands for Durability rather than Data.

Answer each from memory — you'll see instantly whether you're right and why.

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