本题目要求编写SQL语句，查询选修课程超过2门且成绩都在80分以上的学生的姓名、专业及总学分。

提示：请使用SELECT语句作答。

表结构：

CREATE TABLE `major` (
  `mno` char(2) NOT NULL,
  `mname` varchar(20) NOT NULL,
  PRIMARY KEY (`mno`)
);
CREATE TABLE `stu` (
  `sno` char(4) NOT NULL,
  `sname` char(8) NOT NULL,
  `sex` tinyint(1) DEFAULT NULL,
  `mno` char(2) DEFAULT NULL,
  `birdate` datetime DEFAULT NULL,
  `memo` text,
  PRIMARY KEY (`sno`),
  KEY `fk_stu_mno` (`mno`),
  CONSTRAINT `fk_stu_mno` FOREIGN KEY (`mno`) REFERENCES `major` (`mno`)
)；

CREATE TABLE `cou` (
  `cno` char(4) NOT NULL,
  `cname` varchar(30) NOT NULL,
  `credit` smallint(6) DEFAULT NULL,
  `ptime` char(5) DEFAULT NULL,
  `teacher` char(10) DEFAULT NULL,
  PRIMARY KEY (`cno`)
)；

CREATE TABLE `sc` (
  `sno` char(4) NOT NULL,
  `cno` char(4) NOT NULL,
  `grade` decimal(6,1) DEFAULT NULL,
  PRIMARY KEY (`sno`,`cno`),
  KEY `fk_sc_cno` (`cno`),
  CONSTRAINT `fk_sc_cno` FOREIGN KEY (`cno`) REFERENCES `cou` (`cno`),
  CONSTRAINT `fk_sc_sno` FOREIGN KEY (`sno`) REFERENCES `stu` (`sno`)
)

答案参考：

select sname 姓名,mno 专业,sum(credit) 总学分 from stu join sc on stu.sno=sc.sno
join cou on sc.cno=cou.cno
where grade is not null
group by stu.sno 
having count(sname)>=2 and min(grade)>=80