计算tbl_test 表中的两个字段一个是发布时间一个是创建时间，使用变量TIMESTAMPDIFF 来计算二者的差值，

creattime - pubdate。minute的意思是以分钟来做结果单位，limit 2 是两条记录

select TIMESTAMPDIFF(minute, pubdate, createtime)from tbl_test  limit 2;

下面是字段的值和计算结果

+---------------------+---------------------+
| pubdate             | createtime          |
+---------------------+---------------------+
| 2015-06-17 04:59:28 | 2015-06-17 04:59:13 |
| 2015-06-18 13:21:01 | 2015-06-17 10:57:24 |
+---------------------+---------------------+

--------------------------------------------+
| TIMESTAMPDIFF(minute, pubdate, createtime) |
+--------------------------------------------+
|                                          0 |
|                                      -1583 |
+--------------------------------------------+
2 rows in set (0.00 sec)

MySQL 日期、时间相减函数：datediff(date1,date2), timediff(time1,time2)

MySQL datediff(date1,date2)：两个日期相减date1 date2，返回天数。网站制作学习网整理

select datediff('2008-08-08', '2008-08-01'); - 7

select datediff('2008-08-01', '2008-08-08'); -7

MySQL timediff(time1,time2)：两个日期相减time1 time2，返回time 差值。

select timediff('2008-08-08 08:08:08', '2008-08-08 00:00:00');- 08:08:08

select timediff('08:08:08', '00:00:00'); - 08:08:08