sql语句多表联查

4个表

news_info  ,  news_class  ,  city_info  ,  user_info

news_info     字段：id,news_tit，news_content，addDate，tj，city_id

news_class 字段：id,news_class，news_class_fid，news_class_px，user_id

city_info        字段：id,city，fid

user_info     字段：id,username,userEmail

select a.news_tit,a.news_content ,b.news_class,c.city,d.username,d.useremail
 from news_info a,news_class b,city_info c,user_info d
 where a.city_id=c.id and b.user_id=d.id and a.id=b.news_class_fid