Which statement about the SQL INSERT statement is NOT true?

The statement that it defines the database structure is not true regarding the SQL INSERT statement. The INSERT statement is primarily used to add new rows of data to an existing table within a database, which falls under the category of data manipulation language (DML). DML statements are specifically designed for managing the data within the database tables, whereas defining the structure of the database itself, such as creating tables, modifying columns, or changing data types, is typically done using data definition language (DDL) statements like CREATE, ALTER, and DROP.

In addition, while the INSERT statement can be utilized through various user interfaces such as command-line tools, graphical user interfaces, and application programming interfaces, its primary function remains focused on data insertion, not on defining the structure of the database. Therefore, this understanding reinforces that option C accurately describes something that the INSERT statement does not do.