MySQL存储过程-通过数据库里已存在的IP查询城市

CREATE DEFINER=`mazey`@`%` PROCEDURE `sp_find_city_by_ip`(IN `in_visitor_ip` varchar(20),OUT `out_visitor_city` varchar(100))
BEGIN
select visitor_city into out_visitor_city
from record_visitor
where visitor_ip = in_visitor_ip
and timestampdiff(hour,visitor_time,now())<72
limit 1;
if out_visitor_city is null or out_visitor_city = '' THEN
set out_visitor_city=0;
end if;
END

#测试:

call sp_find_city_by_ip('64.74.215.1',@result);
select @result;