如何从MySQL DATETIME实例获取总秒数？
可以使用UNIX_TIMESTAMP()函数，通过以下方式将MySQLDateTime实例转换为秒：
mysql> Select UNIX_TIMESTAMP('2017-05-15 04:05:30') AS 'NUMBER OF SECONDS';
+-------------------+
| NUMBER OF SECONDS |
+-------------------+
| 1494801330 |
+-------------------+
1 row in set (0.00 sec)上面的查询会将给定的datetime实例转换为总秒数。
mysql> Select UNIX_TIMESTAMP(NOW()) AS 'NUMBER OF SECONDS'; +-------------------+ | NUMBER OF SECONDS | +-------------------+ | 1509248856 | +-------------------+ 1 row in set (0.00 sec)
上面的查询会将当前的DateTime实例转换为总秒数。
mysql> Select UNIX_TIMESTAMP(Dateofreg) AS 'NUMBER OF SECONDS' from
testing where StudentName = 'Gaurav';
+-------------------+
| NUMBER OF SECONDS |
+-------------------+
| 1509247113 |
+-------------------+
1 row in set (0.00 sec)上面的查询将转换DateTime实例，该实例是表“testing”中存储值的值，其中StudentName列的值为“Gaurav”。