Displays information about tables and views. If you do not
    specify a wildcard or list of table and view names, SQL displays
    the names of all the tables and views in all attached databases.

    If you do not specify any of the SHOW TABLES options (COLUMNS,
    COMMENT, CONSTRAINTS, INDEXES, STORAGE MAPS, or TRIGGERS), by
    default you will see the display for all these options including
    the character set for each column of the specified table.

    You
    Specify
    This:       SQL Displays Information About:

    COLUMNS     Each column name, data type, and domain name for the
                specified tables.
    COMMENT     Comments for the specified tables.
    CONSTRAINTS Constraints for the specified tables and the
                constraints referencing the specified tables. The
                display shows the name and type of each constraint,
                its evaluation time, and its source definition.