The INSERT statement is used to populate a class with instances:
INSERT INTO weather
    VALUES ('San Francisco', 46, 50, 0.25, '11/27/1994');
    
   You can also use the COPY command to perform load large amounts of data from flat (ASCII) files. This is usually faster because the data is read (or written) as a single atomic transaction directly to or from the target table. An example would be:
COPY weather FROM '/home/user/weather.txt'
    USING DELIMITERS '|';
    
    where the path name for the source file must be available to the
    backend server
    machine, not the client, since the backend server reads the file directly.