Which statement best describes structured data?

• A. Semi-structured data fits into tables and SQL schemas.
• B. Structured data fits into tables and SQL schemas.
• C. Unstructured data lacks any schema that can be tagged.
• D. Structured data cannot be indexed efficiently.

Answer: (B)

Structured data is highly organized data that follows a fixed schema, typically stored in tables with rows and columns. This setup lets databases enforce data types and constraints and enables fast querying through indexing. For example, a customers table with fields like customer_id, name, email, and signup_date has a clear structure that SQL works with efficiently. Because of this rigid schema and uniform formats, structured data fits neatly into tables and SQL schemas, making it easy to search, join, and aggregate.

Semi-structured data has some organization, like tags or partial schemas (think JSON or XML), but it doesn’t adhere to a single rigid table structure. Unstructured data lacks a predefined schema altogether. The claim that structured data cannot be indexed is incorrect, since its fixed schema is what allows efficient indexing and querying.