mysql基础 default 创建有默认值的字段

•        OS : Ubuntu 18.04.1 LTS
•        DBMS : mysql 8.0.12

示例

stu@Ubuntu:~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 26
Server version: 8.0.12 MySQL Community Server - GPL

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use db_chinese_medicine;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> create table `t_default_test`(
    -> `note` varchar(255) default '无' comment'备注，默认：无'
    -> )
    -> ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='测试表';                                                                       Query OK, 0 rows affected (0.12 sec)

mysql> desc t_default_test;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| note  | varchar(255) | YES  |     | 无      |       |
+-------+--------------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql> exit
Bye
stu@Ubuntu:~$ 

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