What is a structured database?

A structured database is a database in which data is stored in a strictly defined, predefined format.

Main characteristics:

• Predictable structure: The data schema (tables, columns, data types, relationships) is defined in advance and maintains data integrity.
• Relational models: Most often built on the principles of the relational model, where data is represented in tables with rows and columns.
• Formal query language: Uses a language such as SQL (Structured Query Language) for managing and querying data.
• Ease of access and management: Thanks to the clear structure, data is easy to search, filter, update, and analyze.

Examples:

• Relational databases (RDBMS): MySQL, PostgreSQL, Oracle, SQL Server.
• Data in electronic spreadsheets with fixed columns.
• Data in CSV or XML format with a strictly defined structure.

Main advantage for QA: Structured data simplifies testing, as it allows clear definition of expected query results and validation of data integrity according to predefined rules.

Example SQL query:

-- Retrieve all records from the 'users' table
SELECT *
FROM users
WHERE status = 'active';