PostgreSQL7.0手册-用户手册-19. SQL命令-COMMENT
2019-09-08 23:33:03
供稿：网友
COMMENT
名称
COMMENT -- 给一个对象增加评注
语法
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'
输入
object_name, table_name, column_name, agg_name, func_name, op, trigger_name
要加入评注的对象名称．
text
要加入的评注．
输出
COMMENT
成功对表评注后的返回．
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
SQL92
SQL92 里没有 COMMENT
