COMMENT

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'

描述

COMMENT 向一个对象里增加评注，这个评注可以很容易用 psql 的 \dd 命令检索出来．要删除一个评注，使用 NULL．当删除对象时，评注自动被删除掉．

用法

给表 mytable　加评注：

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

一些例子：

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 float8 IS 'Computes sample variance';
COMMENT ON FUNCTION my_function (datetime) 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.';

兼容性