comment

COMMENT()			 SQL Commands			    COMMENT()



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’


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

       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 automati-
       cally dropped when the object is dropped.

PARAMETERS
       object_name

       table_name.column_name

       aggname

       constraint_name

       func_name

       op

       rule_name

       trigger_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 new comment.

NOTES
       There is presently no security mechanism for comments: any  user	 con-
       nected  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-critical informa-
       tion in comments.

EXAMPLES
       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_column 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 RI’;
       COMMENT ON TYPE complex IS ’Complex number data type’;
       COMMENT ON VIEW my_view IS ’View of departmental costs’;


COMPATIBILITY
       There is no COMMENT command in the SQL standard.



SQL - Language Statements	  2008-01-03			    COMMENT()