What kind of database contains only one table of data?

A flat-file database is characterized by consisting of a single table that holds all the data without any additional structure. This single table format makes it straightforward and easy to manage, as everything is contained within one location, typically organized in rows and columns like a simple spreadsheet.

In contrast, a relational database consists of multiple tables that can be linked through relationships, allowing for more complex data management and queries. NoSQL databases, which can include various types of data storage models (like document, key-value, or graph), do not conform strictly to the single-table structure and are designed for more scalable and flexible data representation. Hierarchical databases organize data in a tree-like structure, where each record has a single parent and possibly multiple children, further complicating the structure beyond a single table.

Thus, the defining characteristic of a flat-file database is its simplicity, being a standalone table that serves specific use cases for organizing and storing data without the interconnectivity or complexity found in other database types.