试验七部分答案.doc

试验七 Sql 查询语句 目的: 掌握 Select 查询语句。 一 单表1查询年龄在19至21岁之间的女生的学号,姓名,年龄,按年龄从大到小排列。select sno,sname,sage from studentwhere sage between 19 and 21? and ssex=’女’ order by sage desc2查询姓名中第戎2个字为“明”字的学生学号、性别。select sname ,ssex from student where sname like ‘_明%’3查询 1001课程没有成绩的学生学号、课程号select sno,cno? from sc? where grade is null and cno=’1001’4查询JSJ 、SX、WL 系的学生学号,姓名，结果按系及学号排列select sno,sname from student where sdept in (‘JSJ’,’SX’,’WL’)order by sdept,sno 5按10分制查询学生的sno,cno,10分制成绩?? （1-10分 为1 ，11-20分为2 ，30-39分为3，。。。90-100为10）select sno , cno , grade/10.0+1 as level from sc 6查询 student 表中的学生共分布在那几个系中。（distinct）select distinct sdept from student 7查询0001号学生1001，1002课程的成绩。? Select cno from sc where sno=’0001’ and (cno=’1001’ or cno=’1002’) 二 统计1查询姓名中有“明”字的学生人数。select count(*) from student where sname like ‘%明%’2计算‘JSJ’系的平均年龄及最大年龄。? Select avg(sage) , max(sage)? from student Where sdept=’JSJ’3计算每一门课的总分、平均分，最高分、最低分，按平均分由高到低排列? select cno,sum(grade),avg(grade),max(grade),min(grade) from sc? group by cno? order by avg(grade) desc4 计算 1001,1002 课程的平均分。Select cno , avg(grade) from sc? where cno in (‘1001’,’1002’)Group by cno5 查询平均分大于80分的学生学号及平均分select sc.sno , avg(grade) from scgroup by sc.snohaving? avg(grade)806 统计选修课程超过 2 门的学生学号? select sno from sc group by sno having count(*)27 统计有10位成绩大于85分以上的课程号。Select? cno from scwhere grade85group by cno having count(*) =108 统计平均分不及格的学生学号select sno from sc??? group by sno having avg(grade)60 9 统计有大于两门课不及格的学生学号select sno from sc? where? grade60group by sno? having count(*) 2 三 连接1查询 JSJ 系的学生选修的课程号? select cno from student,sc where student.sno=sc.sno and sdept=’JSJ’2查询选修1002 课程的学生的学生姓名 (不用嵌套及嵌套2种方法）a: select sname from? student,sc where student.sno = sc.sno and cno=’1002’b: select sname from student where sno in (select sno from sc where cno=’1002’)3查询数据库原理不及格的学生学号及成绩select sno,grade from sc ,coursewhere sc.cno=course.cno and cname=’数据库原理’4查询选修“数据库原理”课且成绩 80 以上的学生姓名(不用嵌套及嵌套2种方法）a: select sname from stu