COMMENT(l) SQL - Language Statements (2002-11-22) 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'
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_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 comment, write NULL in place of the
text string. Comments are automatically dropped when the
object is dropped.
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COMMENT(l) SQL - Language Statements (2002-11-22) COMMENT(l)
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-critical
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.
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