In SQL, the at sign (@)  means execute. When you type @ and the
    name of an indirect command file, SQL executes the statements in
    that file as if you typed them one-at-a-time at the SQL prompt
    (SQL>). The command file must be a text file that contains SQL
    statements.

    The default file extension for an indirect command file is .SQL.

    You can use the SET VERIFY statement to display the commands in
    the file as they execute.

    SQL recognizes a special SQL command file called SQLINI.SQL,
    which contains SQL statements to be issued before SQL displays
    the SQL prompt (SQL>). If this file exists, SQL executes the
    commands in the file first, before displaying the prompt and
    accepting your input. If you define the logical name to point to
    a general initialization file, SQL uses this file. Otherwise, it
    looks for SQLINI.SQL in the current default directory.