sql多表联合查询……

select *
from Stu_info a,Stu_Message b,Stu_Class c
where a.学生guid=b.学生guid //这里b表中的学生字段根据实际情况定
and b.班级guid=c.编号
group by a.注册日期 desc,b.系部guid asc,班级guid asc

SELECT A.* FROM
Stu_info A INNER JOIN Stu_Message B ON A.学生Guid=B.Guid
INNER JOIN Stu_Depart C ON C.Guid=B.系部Guid
INNER JOIN Stu_Class D ON D.Guid=B.班级Guid
ORDER BY A.注册日期 desc,C.编号,D.编号

select *
from Stu_info a,Stu_Message b,Stu_Depart c,Stu_Class d
where a.学生Guid=b.Guid
and b.系部Guid = c.Guid
and b.班级Guid = d.Guid
order by a.注册日期 desc,c.编号 asc,d.编号 asc