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COMMENT

Name

COMMENT  --  define or change the comment of an object

Synopsis

COMMENT ON
[
  [ DATABASE | INDEX | RULE | SEQUENCE | TABLE | TYPE | VIEW ] object_name |
  COLUMN table_name.column_name |
  AGGREGATE agg_name (agg_type) |
  FUNCTION func_name (arg1, arg2, ...) |
  OPERATOR op (leftoperand_type rightoperand_type) |
  TRIGGER trigger_name ON table_name
] IS 'text'
  

Inputs

object_name, table_name, column_name, agg_name, func_name, op, trigger_name

The name of the object to be be commented.

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.

It should be noted that 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

Comment the table mytable:

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

Some more examples:

COMMENT ON DATABASE my_database IS 'Development Database';
COMMENT ON INDEX my_index IS 'Enforces uniqueness on employee id';
COMMENT ON RULE my_rule IS 'Logs UPDATES of employee records';
COMMENT ON SEQUENCE my_sequence IS 'Used to generate primary keys';
COMMENT ON TABLE my_table IS 'Employee Information';
COMMENT ON TYPE my_type IS 'Complex Number support';
COMMENT ON VIEW my_view IS 'View of departmental costs';
COMMENT ON COLUMN my_table.my_field IS 'Employee ID number';
COMMENT ON AGGREGATE my_aggregate (double precision) IS 'Computes sample variance';
COMMENT ON FUNCTION my_function (timestamp) IS 'Returns Roman Numeral';
COMMENT ON OPERATOR ^ (text, text) IS 'Performs intersection of two text';
COMMENT ON TRIGGER my_trigger ON my_table IS 'Used for R.I.';
   

Compatibility

SQL92

There is no COMMENT in SQL92.

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