COMMENT

3.3.8 COMMENT

Name

COMMENT -- define or change the comment of an object

Synopsis

COMMENT ON
{
  TABLE table_name |
  COLUMN table_name.column_name
} IS 'text'

Description

COMMENT stores a comment about a database object. 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, specify the empty string (two consecutive single quotes with no intervening space) for text. Comments are automatically dropped when the object is dropped.

Parameters

table_name

The name of the table to be commented. The table name may be schema-qualified.

table_name.column_name

The name of a column within table_name to be commented. The table name may be schema-qualified.

text

The new comment.

Notes

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.

Examples

Attach a comment to the table emp:

COMMENT ON TABLE emp IS 'Current employee information';

Attach a comment to the empno column of the emp table:

COMMENT ON COLUMN emp.empno IS 'Employee identification number';

Remove theses comments:

COMMENT ON TABLE emp IS '';
COMMENT ON COLUMN emp.empno IS '';