sql语句
select * from think_neirong a,think_class b where a.class_id=b.id
thinkphp语句
$Neirong = M("Neirong");
$con = $Neirong->alias(‘a‘)->join(‘think_class b ON a.class_id= b.id‘)->select();具体详解看thinkphp手册 alias函数
原文：http://blog.csdn.net/genziisme/article/details/45818517