This PostgreSQL SQL query gets a list of distinct class IDs from the "students" record. Even if a class ID has several students linked with it, the statement ensures that each class ID is only listed once by using the term "DISTINCT".
This SQL statement has to be typed into a SQL editor or command-line application that can interact with a PostgreSQL database in order to be executed. A list of unique class IDs connected to the students in the "students" table will be the query's output.