redhat man page for comment

COMMENT(7)							   SQL Commands 							COMMENT(7)

NAME
       COMMENT - define or change the comment of an object

SYNOPSIS
       COMMENT ON
       [
	 TABLE object_name |
	 COLUMN table_name.column_name |
	 AGGREGATE agg_name (agg_type) |
	 CONSTRAINT constraint_name ON table_name |
	 DATABASE object_name |
	 DOMAIN object_name |
	 FUNCTION func_name (arg1_type, arg2_type, ...) |
	 INDEX object_name |
	 OPERATOR op (leftoperand_type, rightoperand_type) |
	 RULE rule_name ON table_name |
	 SCHEMA object_name |
	 SEQUENCE object_name |
	 TRIGGER trigger_name ON table_name |
	 TYPE object_name |
	 VIEW object_name
       ] IS 'text'

   INPUTS
       object_name,
	      The  name  of  the object to be be commented. Names of tables, aggregates, domains, functions, indexes, operators, sequences, types,
	      and views may be schema-qualified.

       text   The comment to add.

   OUTPUTS
       COMMENT
	      Message returned if the table is successfully commented.

DESCRIPTION
       COMMENT stores a comment about a database object.  Comments can be easily retrieved with psql's dd,  d+,  or  l+  commands.  Other  user
       interfaces  to  retrieve  comments  can be built atop the same built-in functions that psql uses, namely obj_description() and col_descrip-
       tion().

       To modify a comment, issue a new COMMENT command for the same object. Only one comment string is stored for each object.  To remove a  com-
       ment, write NULL in place of the text string.  Comments are automatically dropped when the object is dropped.

	      Note:  There  is presently no security mechanism for comments: any user connected to a database can see all the comments for objects
	      in that database (although only superusers can change comments for objects that they don't own). Therefore, don't put security-crit-
	      ical information in comments.

USAGE
       Attach a comment to the table mytable:

       COMMENT ON TABLE mytable IS 'This is my table.';

       Remove it again:

       COMMENT ON TABLE mytable IS NULL;

       Some more examples:

       COMMENT ON AGGREGATE my_aggregate (double precision) IS 'Computes sample variance';
       COMMENT ON COLUMN my_table.my_field IS 'Employee ID number';
       COMMENT ON DATABASE my_database IS 'Development Database';
       COMMENT ON DOMAIN my_domain IS 'Email Address Domain';
       COMMENT ON FUNCTION my_function (timestamp) IS 'Returns Roman Numeral';
       COMMENT ON INDEX my_index IS 'Enforces uniqueness on employee id';
       COMMENT ON OPERATOR ^ (text, text) IS 'Performs intersection of two texts';
       COMMENT ON OPERATOR ^ (NONE, text) IS 'This is a prefix operator on text';
       COMMENT ON RULE my_rule ON my_table IS 'Logs UPDATES of employee records';
       COMMENT ON SCHEMA my_schema IS 'Departmental data';
       COMMENT ON SEQUENCE my_sequence IS 'Used to generate primary keys';
       COMMENT ON TABLE my_schema.my_table IS 'Employee Information';
       COMMENT ON TRIGGER my_trigger ON my_table IS 'Used for R.I.';
       COMMENT ON TYPE complex IS 'Complex Number datatype';
       COMMENT ON VIEW my_view IS 'View of departmental costs';

COMPATIBILITY
   SQL92
       There is no COMMENT in SQL92.

SQL - Language Statements					    2002-11-22								COMMENT(7)