我正在运行一个查询：
select
iars.id,students.rollno,
students.name as name,
teachers.name as tname,
students.studentid,
t1.studentid,
sum(t1.obt) as obt1, sum(t1.benefits) as ben1, sum(t1.max) as max1,
(t2.obt) as obt2, (t2.benefits) as ben2, (t2.max) as max2,
(t3.obt) as obt3, (t3.benefits) as ben3, (t3.max) as max3,
(t4.obt) as obt4, (t4.benefits) as ben4, (t4.max) as max4,
(t5.obt) as obt5, (t5.benefits) as ben5, (t5.max) as max5
from groups,students
left join iars on iars.id
left join str on str.studentid=students.studentid
left join course on course.c_id=students.course
left join teachers on teachers.id=iars.teacherid
join sgm on sgm.studentid=students.studentid
left join semdef on month
left join sps on sps.studentid=students.studentid and iars.paperid=sps.paperid
left join `attndata` `t1` on ((t1.studentid=students.studentid) and iars.id=t1.iarsid and t1.mon=1)
left join `attndata` `t2` on ((t1.studentid=t2.studentid) and t2.mon = 2 and iars.id=t2.iarsid)
left join `attndata` `t3` on ((t2.studentid=t3.studentid) and t3.mon = 4 and iars.id=t3.iarsid)
left join `attndata` `t4` on ((t3.studentid=t4.studentid) and t4.mon = 5 and iars.id=t4.iarsid)
left join `attndata` `t5` on ((t4.studentid=t5.studentid) and t5.mon = 6 and iars.id=t5.iarsid)
where students.course='1' and students.status='regular' and sps.paperid='2' and
iars.courseid=students.course and iars.semester=str.semesterid and iars.paperid='2' and
str.semesterid='1' and str.sessionid='12' and groups.id=sgm.groupid
group by sps.studentid , teachers.id order by students.name
它是分组的，就像我想根据月份计算总和，但每当我使用总和时，它都会给我带来有趣的结果。