Oracle中date类型对应 MySQL 时间类型以及空值的处理
因为在做Oracle---->MySQL的数据迁移的时候，发现Oracle中的date类型，对应的MySQL的时间类型设置不当容易引起错误，特别是存在空值的时候
MySQL 版本 5.6.40版本
mysql> desc t1;
+-------------+-----------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+-----------+------+-----+-------------------+-----------------------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| time_1 | time | YES | | NULL | |
| date_2 | date | YES | | NULL | |
| datetime_3 | datetime | YES | | NULL | |
| timestamp_4 | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-------------+-----------+------+-----+-------------------+-----------------------------+
5 rows in set (0.00 sec)
可以插入当前的时间
mysql> insert into t1 values(null,now(),now(),now(),now());
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> show warnings;
+-------+------+--------------------------------------------------------------------------+
| Level | Code | Message |
+-------+------+--------------------------------------------------------------------------+
| Note | 1292 | Incorrect date value: '2018-05-11 11:18:41' for column 'date_2' at row 1 |
+-------+------+--------------------------------------------------------------------------+
1 row in set (0.00 sec)
提示date类型插入告警，但是依旧可以插入进去，因为date类型只记录年月（yyyy-mm）
Query OK, 1 row affected (0.01 sec)
4个时间空值插入测试 ，time类型，插入0
mysql> insert into t1 values (null,'0','2018-01-01','2018-01-01 12:12:12','2018-10-10 00:00:00');
Query OK, 1 row affected (0.01 sec)
mysql> select * from t1;
+----+----------+------------+---------------------+---------------------+
| id | time_1 | date_2 | datetime_3 | timestamp_4 |
+----+----------+------------+---------------------+---------------------+
| 1 | 22:21:23 | 2018-05-08 | 2018-05-08 22:21:23 | 2018-05-08 22:21:23 |
| 2 | 22:21:54 | 2018-05-08 | 2018-05-08 22:21:54 | 2018-05-08 22:21:54 |
| 3 | 00:00:00 | 2018-01-01 | 2018-01-01 12:12:12 | 2018-10-10 00:00:00 | time_1 自动填充为00:00:00
| 4 | 00:00:00 | 2018-01-01 | 2018-01-01 12:12:12 | 2018-10-10 00:00:00 |
+----+----------+------------+---------------------+---------------------+
4 rows in set (0.00 sec)
接着全部插入0，看是否能够插入进去
测试date类型---------------
第三列为date类型
mysql> insert into t1 values(null,'0','0','0','0'); 插入 0
ERROR 1292 (22007): Incorrect date value: '0' for column 'date_2' at row 1
mysql> insert into t1 values(null,'0','','0','0'); 插入‘ ’测试，留空白，测试插入
ERROR 1292 (22007): Incorrect date value: '' for column 'date_2' at row 1
mysql> insert into t1 values(null,'0','null','0','0'); 插入 null 测试
ERROR 1292 (22007): Incorrect date value: 'null' for column 'date_2' at row 1
-------------测试datetime类型--
第四列为datetime类型
mysql> insert into t1 values(null,'0',null,'0','0');
ERROR 1292 (22007): Incorrect datetime value: '0' for column 'datetime_3' at row 1
插入null成功
---------测试timestamp类型
第五列为timestamp
mysql> insert into t1 values(null,'0',null,null,'0');
ERROR 1292 (22007): Incorrect datetime value: '0' for column 'timestamp_4' at row 1
mysql> insert into t1 values(null,'0',null,null,null);
Query OK, 1 row affected (0.00 sec)
插入null 成功
mysql> select * from t1;
+----+----------+------------+---------------------+---------------------+
| id | time_1 | date_2 | datetime_3 | timestamp_4 |
+----+----------+------------+---------------------+---------------------+
| 1 | 22:21:23 | 2018-05-08 | 2018-05-08 22:21:23 | 2018-05-08 22:21:23 |
| 2 | 22:21:54 | 2018-05-08 | 2018-05-08 22:21:54 | 2018-05-08 22:21:54 |
| 3 | 00:00:00 | 2018-01-01 | 2018-01-01 12:12:12 | 2018-10-10 00:00:00 |
| 4 | 00:00:00 | 2018-01-01 | 2018-01-01 12:12:12 | 2018-10-10 00:00:00 |
| 5 | 00:00:00 | NULL | NULL | 2018-05-08 22:33:22 |
+----+----------+------------+---------------------+---------------------+
5 rows in set (0.00 sec)
总结 ： Oracle数据库的date类型和mysql的date类型是不一样的，Oracle为yyyy-mm-dd hh:mi:ss和mysql中的datetime类型匹配， 而 mysql 为 yyyy-mm 。当在存在空值的时候，mysql的time 类型可以使用0零来插入，而date，datetime，timestamp可以使用null 来插入，但是timestamp即使为null，也会默认插入当前时间戳。