Which output format is NOT supported by the SET SQLFORMAT command?

The correct option indicates that the TXT format is not supported by the SET SQLFORMAT command when working with SQL output formatting in certain database systems. The other formats—HTML, XML, and CSV—are commonly supported by SQL database systems to allow for versatile data presentation and integration.

HTML is useful for displaying query results directly in web formats, giving an organized and visually appealing output. XML provides a structured format that is beneficial for data interchange between systems, as it allows for both human-readable and machine-readable structures. CSV, or Comma-Separated Values, is widely used for exporting data to spreadsheets and other applications due to its simplicity and compatibility.

In contrast, TXT format, while implying plain text output, does not have the same level of structured presentation or standardized delimiters as the other options, which is likely why it is not supported by the SET SQLFORMAT command in this context. This distinction helps users understand the intended use and limitations of the SQL formatting capabilities within their database environment.