吃水不忘挖井人

先看mysql一个简单的变量查询： SET @rowNum = 0; SELECT ( @rowNum := @rowNum + 1 ) AS rankNum; 变量初始值rowNum设置为0，查询一行数据变量+1，定义为排行号，也是数据行号 用途一：数据排行 现在签到表结构如下： CREATE TABLE `sign_in` ( `phone` varchar(11) NOT NULL COMMENT '登录手机号', `integral_num` decimal(3,0) NOT

还拿上篇中sql举例： SET @rowNum = 0; SELECT ( @rowNum := @rowNum + 1 ) AS rowNo, t.phone, t.count FROM ( SELECT phone, count( 1 ) AS count FROM sign_in GROUP BY phone ORDER BY count DESC LIMIT 10 ) t; 方法一：合并成一条语句 SELECT ( @rowNum := @rowNum + 1 ) AS r