COMMENT ON

comment_on ::= COMMENT ON object_type object_name IS 'comment_text'
             | COMMENT ON object_type object_name IS NULL

object_type ::= COLUMN | FUNCTION | INDEX | PROCEDURE | TABLE | VIEW

object_name ::= [schema.]name
              | [schema.]table_name.column_name                -- for columns
              | [schema.]function_name(argument_types)         -- for functions
              | [schema.]procedure_name(argument_types)        -- for procedures