COMMENT(l)

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 eas-
       ily 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 data-
       base  (although  only  superusers  can change comments for objects that
       they don't own). Therefore, don't put security-critical information  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         2003-11-02                        COMMENT(l)