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代码格式:
CREATE TABLE table_name
(
timestamp_name TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);
示例:
mysql> desc test;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| username | varchar(16) | YES | UNI | NULL | |
| version | int(3) | YES | | NULL | |
+----------+-------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)
mysql> alter table test drop column version;
Query OK, 0 rows affected (0.20 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> alter table test add column time TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP;
Query OK, 0 rows affected (0.25 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc test;
+----------+-------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+-------------------+-----------------------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| username | varchar(16) | YES | UNI | NULL | |
| time | timestamp | YES | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+----------+-------------+------+-----+-------------------+-----------------------------+
3 rows in set (0.00 sec)
mysql> insert into test(username) values('mary');
Query OK, 1 row affected (0.08 sec)
mysql> select * from test;
+----+-----------+---------------------+
| id | username | time |
+----+-----------+---------------------+
| 1 | zhangsan4 | 2018-07-10 20:19:13 |
| 2 | mary | 2018-07-10 20:21:14 |
+----+-----------+---------------------+
2 rows in set (0.00 sec)
mysql> update test set username='lisa' where id=2;
Query OK, 1 row affected (0.10 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from test;
+----+-----------+---------------------+
| id | username | time |
+----+-----------+---------------------+
| 1 | zhangsan4 | 2018-07-10 20:19:13 |
| 2 | lisa | 2018-07-10 20:22:42 |
+----+-----------+---------------------+
2 rows in set (0.00 sec)