MySQL脚本优化

我有两个MySQL表，

graphics

，

rasp

：

我的查询工作正常，但速度太慢（限制1大约200秒以上，并且只有大约50000条记录）

我需要从

graphics

中选择1个记录中的2个（结果记录）：

我的问题是：

SELECT r.num, r.from, r.to, g.id, g.comment, g.stationid1, g2.id, g2.comment, g2.stationid1 
FROM graphics g, graphics g2, rasp r 
WHERE abs(timestampdiff(minute,g.dt,CONCAT(g.date,' ',r.from)))<30 
    AND g2.id>g.id 
    AND g.stationid1=r.stationfrom 
    AND abs(timestampdiff(minute,g2.dt,CONCAT(g2.date,' ',r.to)))<30 
    AND g2.stationid2=r.stationto 
    AND g.date=g2.date 
    AND g.trainid=g2.trainid 
group by g.date, g.comment 
LIMIT 1

选择r.num、r.from、r.to、g.id、g.comment、g.stationid1、g2.id、g2.comment、g2.stationid1
从图形g、图形g2、锉刀r
其中abs（timestampdiff（分钟，g.dt，CONCAT（g.date，，，r.from））g.id
g.stationd1=r.stationfrom
和abs（timestampdiff（minute，g2.dt，CONCAT（g2.date，，，r.to）））表上有什么索引？EXPLAIN对查询有什么解释？EXPLAIN Barmar，索引解决了我的问题，谢谢
SELECT r.num, r.from, r.to, g.id, g.comment, g.stationid1, g2.id, g2.comment, g2.stationid1 
FROM graphics g, graphics g2, rasp r 
WHERE abs(timestampdiff(minute,g.dt,CONCAT(g.date,' ',r.from)))<30 
    AND g2.id>g.id 
    AND g.stationid1=r.stationfrom 
    AND abs(timestampdiff(minute,g2.dt,CONCAT(g2.date,' ',r.to)))<30 
    AND g2.stationid2=r.stationto 
    AND g.date=g2.date 
    AND g.trainid=g2.trainid 
group by g.date, g.comment 
LIMIT 1