我有一张包含一些记录的表格。现在我想向其中添加“创建”和“更新”列。我正在使用这样的查询
ALTER TABLE employee ADD COLUMN updated TIMESTAMP NOT NULL DEFAULT
CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP;
但这是创建值全为零的列。我希望它是当前时间戳。
示例:
mysql> select * from employee;
+----+------+
| id | name |
+----+------+
| 1 | a |
| 2 | b |
| 3 | c |
+----+------+
3 rows in set (0.00 sec)
mysql> alter table employee add column updated timestamp not null default current_timestamp on update current_timestamp;
Query OK, 3 rows affected (0.20 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from employee;
+----+------+---------------------+
| id | name | updated |
+----+------+---------------------+
| 1 | a | 0000-00-00 00:00:00 |
| 2 | b | 0000-00-00 00:00:00 |
| 3 | c | 0000-00-00 00:00:00 |
+----+------+---------------------+
3 rows in set (0.00 sec)
mysql> update employee set name='aa' where id='1';
Query OK, 1 row affected (0.05 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from employee;
+----+------+---------------------+
| id | name | updated |
+----+------+---------------------+
| 1 | aa | 2015-12-10 15:41:44 |
| 2 | b | 0000-00-00 00:00:00 |
| 3 | c | 0000-00-00 00:00:00 |
+----+------+---------------------+
3 rows in set (0.00 sec)
mysql> alter table employee add column city varchar(10) not null default 'banglore';
Query OK, 3 rows affected (0.17 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from employee;
+----+------+---------------------+----------+
| id | name | updated | city |
+----+------+---------------------+----------+
| 1 | aa | 2015-12-10 15:41:44 | banglore |
| 2 | b | 0000-00-00 00:00:00 | banglore |
| 3 | c | 0000-00-00 00:00:00 | banglore |
+----+------+---------------------+----------+
3 rows in set (0.00 sec)
似乎 DEFAULT CURRENT_TIMESTAMP 不起作用
最佳答案
ALTER TABLE `employee` ADD `COLUMN`
TIMESTAMP on update CURRENT_TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
关于mysql - 将创建时间，修改时间列添加到mysql中的现有表，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34197351/