<![CDATA[向东博客 专注WEB应用 构架之美 --- 构架之美，在于尽态极妍 | 应用之美，在于药到病除]]> http://jackxiang.com/index.php zh-cn http://jackxiang.com/post// <![CDATA[表中FTime字段是date时间分秒都有在查询某天的登录用户数的一个sql语句]]> jack <xdy108@126.com> Tue, 27 Jul 2010 05:30:03 +0000 http://jackxiang.com/post//
mysql> select  left(now(),7);
+---------------+
| left(now(),7) |
+---------------+
| 2010-09       |
+---------------+
1 row in set (0.00 sec)

mysql> select  now();
+---------------------+
| now()               |
+---------------------+
| 2010-09-21 13:40:37 |
+---------------------+
1 row in set (0.00 sec

select left(FTime,10),count(*) from Tbl_User    group by left(FTime,10) ;

+----------------+----------+
| left(FTime,10) | count(*) |
+----------------+----------+
|                |     1044 |
| 2010-07-21     |        6 |
| 2010-07-22     |     2746 |
| 2010-07-23     |    10273 |
| 2010-07-24     |     7691 |
| 2010-07-25     |     6955 |
| 2010-07-26     |     7622 |
| 2010-07-27     |     2130 |
+----------------+----------+

注意下面查询语句的区别：
mysql> select left(FTime,10),count(*) from Tbl_User    group by left(FTime,10) ;
+----------------+----------+
| left(FTime,10) | count(*) |
+----------------+----------+
|                |        1 |
| 2010-07-13     |        7 |
| 2010-07-14     |        1 |
| 2010-07-15     |        1 |
| 2010-07-16     |        3 |
| 2010-07-20     |        2 |
| 2010-07-25     |        1 |
+----------------+----------+
7 rows in set (0.00 sec)

mysql> select FTime,count(*) from Tbl_User    group by left(FTime,10) ;        
+---------------------+----------+
| FTime               | count(*) |
+---------------------+----------+
|                     |        1 |
| 2010-07-13 11:39:45 |        7 |
| 2010-07-14 11:50:20 |        1 |
| 2010-07-15 15:16:20 |        1 |
| 2010-07-16 16:11:39 |        3 |
| 2010-07-20 12:00:31 |        2 |
| 2010-07-25 19:16:08 |        1 |
+---------------------+----------+
FTime类型如下：

`FTime` varchar(32) collate utf8_bin NOT NULL,
]]> http://jackxiang.com/post//#blogcomment <![CDATA[[评论] 表中FTime字段是date时间分秒都有在查询某天的登录用户数的一个sql语句]]> <user@domain.com> Thu, 01 Jan 1970 00:00:00 +0000 http://jackxiang.com/post//#blogcomment