What type of databases use structured tables and are commonly accessed through SQL?

Relational databases are built upon the use of structured tables to organize data effectively. In these databases, the data is stored in tables that consist of rows and columns, where each row represents a unique record and each column represents an attribute of that record. This structure allows for logical organization, efficient data retrieval, and ensures that data integrity can be maintained through relationships between tables.

Structured Query Language (SQL) is the standard language used to interact with relational databases. It provides the means to perform various operations such as querying data, inserting new records, updating existing records, and deleting data. The relational model, grounded in mathematics, ensures that complex queries can be made through joins, aggregations, and filtering, all of which are facilitated by SQL.

In contrast, other types of databases have different structures and access methods. NoSQL databases typically use unstructured or semi-structured data models and are not primarily accessed using SQL. Flat-file databases are even simpler, consisting of a single table without the relational capabilities that SQL provides. Distributed databases might span multiple locations but can still include relational databases among them.