What is the main purpose of a schema in a database?

The main purpose of a schema in a database is to define the organization and structure of data. A schema serves as a blueprint that outlines how data is organized, including the tables, fields, data types, and relationships between tables. This structure is essential for ensuring that data is stored efficiently, accessed accurately, and manipulated appropriately.

Schemas help maintain the integrity of the data by establishing rules about how data can be entered and how it relates to other data, which allows for effective data management and manipulation. In a well-designed schema, entities and attributes are clearly defined, making it easier for users to understand how to interact with the data and for applications to retrieve and use it properly.

The other options, while related to database management tasks, do not capture the primary role of a schema. User permissions relate to security and access control, cataloging visualizations pertains to data presentation rather than structure, and importing and exporting data focuses on data transfer processes instead of the underlying organization of that data. Therefore, the emphasis on structure in conjunction with data integrity truly defines the core purpose of a schema in a database.