在5.5到5.6.4版本里，對於DEFAULT CURRENT_TIMESTAMP子句，只能TIMESTAMP型別列上指定。

而從5.6.5開始（也包括5.7），DEFAULT CURRENT_TIMESTAMP子句可以指定到TIMESTAMP或者DATETIME型別列上。

比如在5.5中：

mysql> select version();
+------------+
| version()  |
+------------+
| 5.5.48-log |
+------------+
1 row in set (0.00 sec)

mysql> use test;
Database changed
mysql> create table t1(id int, dt timestamp not null DEFAULT CURRENT_TIMESTAMP, dt1 datetime not null DEFAULT CURRENT_TIMESTAMP);
ERROR 1067 (42000): Invalid default value for 'dt1'
mysql>

而在5.7中：

mysql> select version();
+------------+
| version()  |
+------------+
| 5.7.11-log |
+------------+
1 row in set (0.00 sec)

mysql> use test;
Database changed
mysql> create table t1(id int, dt timestamp not null DEFAULT CURRENT_TIMESTAMP, dt1 datetime not null DEFAULT CURRENT_TIMESTAMP);
ERROR 1050 (42S01): Table 't1' already exists
mysql> drop table t1;
Query OK, 0 rows affected (0.38 sec)

mysql> create table t1(id int, dt timestamp not null DEFAULT CURRENT_TIMESTAMP, dt1 datetime not null DEFAULT CURRENT_TIMESTAMP);
Query OK, 0 rows affected (0.32 sec)

mysql> desc t1;
+-------+-----------+------+-----+-------------------+-------+
| Field | Type      | Null | Key | Default           | Extra |
+-------+-----------+------+-----+-------------------+-------+
| id    | int(11)   | YES  |     | NULL              |       |
| dt    | timestamp | NO   |     | CURRENT_TIMESTAMP |       |
| dt1   | datetime  | NO   |     | CURRENT_TIMESTAMP |       |
+-------+-----------+------+-----+-------------------+-------+
3 rows in set (0.10 sec)

mysql>
--------------------- 
作者：q3dxdx 
來源：CSDN 
原文：https://blog.csdn.net/q3dxdx/article/details/50948360 
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