What type of database contains only one table of data?

A flat-file database is defined by its structure of consisting of a single table that holds all the data. This type of database is simple and easy to understand, making it suitable for small datasets where complex relationships between data aren't necessary. It stores data in rows and columns, similar to a spreadsheet, where each row represents a record and each column represents a field.

In contrast, a relational database comprises multiple tables that can be linked through relationships, allowing for more complex data management and queries. A hierarchical database organizes data in a tree-like structure with parent-child relationships, which can complicate access to data. A NoSQL database encompasses a variety of database technologies that allow for unstructured and semi-structured data, accommodating multiple data storage models that are generally more complex than a flat-file system. Each of these alternatives provides capabilities beyond a single table structure, which is characteristic of a flat-file database.