Which statement is accurate about SQL and NoSQL databases?

• A. SQL databases are non-relational with flexible schemas.
• B. NoSQL databases are relational with fixed schemas.
• C. SQL databases are relational with fixed schemas and use SQL queries; NoSQL databases are non-relational with flexible schemas, suitable for unstructured data and scalability.
• D. Both are identical in data models and query languages.

Answer: (C)

Relational databases organize data into tables with a fixed schema and use SQL to query them. NoSQL databases embrace non-relational models with flexible schemas, making them suitable for unstructured or semi-structured data and often easier to scale horizontally. This combination—SQL databases being relational with fixed schemas and using SQL queries, while NoSQL databases are non-relational with flexible schemas geared toward unstructured data and scalability—best captures the real differences.

Options that flip these ideas (SQL as non-relational with flexible schemas, or NoSQL as relational with fixed schemas) or claim there’s no difference don’t fit because they misstate the core distinctions.