摘要： DROP TABLE IF EXISTS `log`; CREATE TABLE `log` ( `log_id` bigint(20) NOT NULL auto_increment, `device_ip` varchar(23) NOT NULL, `severity` tinyint(1) NOT NULL, PRIMARY KEY (`log_id`) ) ENGIN... 阅读全文

摘要： 在mysql 下执行如下命令：select use_city,count(*) from data where os="Windows 2003 Std" group by use_city;得到的结果为： +-----------+----------+ | use_city | count(*) | +-----------+----------+ | Beijing | ... 阅读全文