表结构:tableName(cgi,lo,la,derection,city)
SQL:
SELECT
t1.cgi AS s_cgi,
t1.lo AS s_lo,
t1.derection AS s_derection,
t2.cgi AS t_cgi,
t2.lo AS t_lo,
t2.derection AS t_derection
FROM
tableName t1,
tableName t2
WHERE
t1.city = 'GZ'
AND t2.city = 'GZ'
我确实是需要这样的结果。这样的语句在数据很大的时候木有性能可言,原表8000条数据都要查好几个小时,请大神指导,整一个速度有很大提升法子,主要在数据端处理,PostgreSQL。求解决方案!!!!!!虽说没有什么分,但是还是想跟大学学习下多谢!