UNIX_TIMESTAMP(), UNIX_TIMESTAMP(date)

如果調用不帶參數，返回一個UNIX時間戳(自“1970-01-0100:00:00”UTC)的一個無符號整數。如果UNIX_TIMESTAMP()被調用帶有日期參數，它返回的參數為秒，自“1970-01-0100:00:00”UTC的值。日期可能是日期字符串，時間字符串，一個TIMESTAMP或數字格式YYMMDD或YYYYMMDD。

mysql> SELECT UNIX_TIMESTAMP();
+---------------------------------------------------------+
| UNIX_TIMESTAMP()                                        |
+---------------------------------------------------------+
| 882226357                                               |
+---------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SELECT UNIX_TIMESTAMP('1997-10-04 22:23:00');
+---------------------------------------------------------+
| UNIX_TIMESTAMP('1997-10-04 22:23:00')                   |
+---------------------------------------------------------+
| 875996580                                               |
+---------------------------------------------------------+
1 row in set (0.00 sec)