PostgreSQL7.0手冊(cè)-用戶手冊(cè)-19. SQL命令-COMMENT
2019-09-08 23:33:03
供稿：網(wǎng)友
COMMENT
名稱
COMMENT -- 給一個(gè)對(duì)象增加評(píng)注
語法
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'
輸入
object_name, table_name, column_name, agg_name, func_name, op, trigger_name
要加入評(píng)注的對(duì)象名稱．
text
要加入的評(píng)注．
輸出
COMMENT
成功對(duì)表評(píng)注后的返回．
描述
COMMENT 向一個(gè)對(duì)象里增加評(píng)注，這個(gè)評(píng)注可以很容易用 psql 的 /dd 命令檢索出來．要?jiǎng)h除一個(gè)評(píng)注，使用 NULL．當(dāng)刪除對(duì)象時(shí)，評(píng)注自動(dòng)被刪除掉．
用法
給表 mytable 加評(píng)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 里沒有 COMMENT
