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  • 数据库学习7-28

    select * from STUDENT;

    select * from STU_COURSE;

    select * from SCLASS;

    select * from MAJOR;

    select * from COURSE;

    1.查询所有学员姓名,年龄(显示整数,如24.75岁显示为24岁),所学专业名称,所属班级名称

      select STU_NAME,

             CLASS_NAME,

             MAJOR_NAME,

             round (months_between(sysdate , s.stu_birthday) / 12)

          from STUDENT s, MAJOR m, SCLASS c

         where s.STU_MAJOR = m.major_id

           and s.stu_class = c.class_id;

    2.查询专业编号,专业名称,专业人数

     select MAJOR_ID,MAJOR_NAME,count(s.STU_ID)

     from MAJOR m,STUDENT s

     where m.MAJOR_ID=s.STU_MAJOR(+)

     group by  MAJOR_ID,MAJOR_NAME;

    3.查询员学号,学员姓名,其平均分,并按照平均分由高至低排序

     select s.STU_ID, STU_NAME, avgSCORE

       from STUDENT s,

            STU_COURSE c,

            (select STU_ID, avg(SCORE) avgSCORE

               from STU_COURSE

              group by STU_ID) d

      where s.STU_ID = c.STU_ID

        and s.STU_ID = d.STU_ID

      order by avgSCORE desc;

    4.查询在701课程上,分数高于平均分的学生信息和考试分数

     select s.*, SCORE

       from STUDENT s, STU_COURSE c

      where s.STU_ID = c.STU_ID

        and c.COURSE_ID = 701

        and SCORE > (select avg(SCORE) from STU_COURSE where c.COURSE_ID =701);

    5.查询已修得学分超过6分的学生信息(所选考试分数不低于60视为修的学分)

     select *

        from student

       where stu_id in (select s.stu_id

                         from student s, stu_course sc, course c

                        where s.stu_id = sc.stu_id

                          and sc.course_id = c.c_id

                          and sc.score >= 60

                        group by s.stu_id

                       having sum(c_score) > 6);

    6.查询所有科目不及格(考试分数低于60)的学员的信息

     select *

       from STUDENT s   where not exists (select 1

              from stu_course sc

             where s.stu_id = sc.stu_id

               and SCORE >= 60);

    7.查询所有科目平均分高于80的学生的学号,姓名,所在班级名称,平均分

     select s.STU_ID, s.STU_NAME, c.CLASS_NAME, avg(t.score)

       from STUDENT s, SCLASS c, STU_COURSE t

      where s.stu_class = c.class_id     and s.stu_id = t.stu_id having avg(t.score) > 80

      group by s.STU_ID, s.STU_NAME, c.CLASS_NAME;

    8.查询所有科目平均分比学生lu的平均分高的学生

     select *    from STUDENT   where STU_ID in

           (select s.STU_ID

              from STUDENT s, STU_COURSE t

             where s.stu_id = t.stu_id having

             avg(score) > (select avg(score)

                                   from STU_COURSE t, STUDENT s

                                  where STU_NAME = 'Lu'

                                    and s.stu_id = t.stu_id)

             group by s.STU_ID);

    9.查询各班级名称,人数和考试总分(班级所有学生各项考试分数求和)

     select CLASS_NAME, count(distinct s.STU_ID), sum(SCORE)

       from STU_COURSE t, SCLASS c, STUDENT s

      where s.stu_class = c.class_id(+)

        and s.stu_id = t.stu_id   group by CLASS_NAME;

    10.查询班级人数高于各班级平均人数的班级编号,班级名称

     select CLASS_ID, CLASS_NAME

       from SCLASS c, STUDENT s

      where s.stu_class = c.class_id having   count(stu_id) >

            (select avg(count(stu_id)) from STUDENT group by STU_CLASS)

      group by CLASS_ID, CLASS_NAME;

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  • 原文地址:https://www.cnblogs.com/hole/p/11261008.html
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