mysql 查询时额外查询一个index列，类似sqlserver的ROW_NUMBER()

-- 创建临时表
CREATE TEMPORARY TABLE temp1 AS (
　　SELECT (@rowindex := @rowindex +1) AS rowindex,a.city_id,b.name as 'city_name' ,a.dept_name,a.final_point
　　FROM aqjd_assessment_dept a 
　　JOIN sys_city b on a.city_id = b.id 
　　JOIN (SELECT (@rowindex := 0)) c  -- rowindex 初始化
　　WHERE a.city_station =1 
　　ORDER BY a.final_point DESC 
);