Oracle 查询语句练习（二）

表结构及数据

-- 学生信息表
SELECT *
  FROM hand_student;

--教师信息表
SELECT *
  FROM hand_teacher;

--课程信息表
SELECT *
  FROM hand_course;

--成绩信息表
SELECT *
  FROM hand_student_core;

-- 学生信息表
SELECT *
  FROM hand_student;

--教师信息表
SELECT *
  FROM hand_teacher;

--课程信息表
SELECT *
  FROM hand_course;

--成绩信息表
SELECT *
  FROM hand_student_core;

--1.	查询没学过“谌燕”老师课的同学，显示（学号、姓名）
--方法一：
SELECT stu.student_no,
       stu.student_name
  FROM hand_student stu
 WHERE stu.student_no NOT IN (SELECT core.student_no
                                FROM hand_student_core core
                               WHERE core.course_no IN (SELECT course.course_no
                                                          FROM hand_course course
                                                         WHERE course.teacher_no IN (SELECT tea.teacher_no
                                                                                       FROM hand_teacher tea
                                                                                      WHERE tea.teacher_name = '谌燕')
                                                           AND course.course_no IS NOT NULL));
 --方法二：（优先使用）
 SELECT hs.student_no, 
       hs.student_name
  FROM hand_student hs
 WHERE NOT EXISTS (SELECT 1
                     FROM hand_course hc, hand_teacher ht, hand_student_core hsc
                    WHERE hc.teacher_no = ht.teacher_no
                      AND hc.course_no = hsc.course_no
                      AND ht.teacher_name = '谌燕'
                      AND hsc.student_no = hs.student_no);                                                          

--2.	查询没有学全所有课的同学，显示（学号、姓名）

SELECT stu.student_no,stu.student_name
  FROM hand_student stu
 WHERE stu.student_no IN (SELECT core.student_no
                 FROM hand_student_core core
                GROUP BY core.student_no
               HAVING COUNT(*) < (SELECT COUNT(*)
                                   FROM hand_course));

--3.	查询“c001”课程比“c002”课程成绩高的所有学生，显示（学号、姓名）
---误解题意
SELECT stu.student_no,
       stu.student_name
  FROM hand_student stu
 WHERE stu.student_no IN (SELECT c2.student_no
                            FROM hand_student_core c2
                           WHERE c2.core > (SELECT MAX(c.core)
                                              FROM hand_student_core c
                                             WHERE c.course_no = 'c002')
                             AND c2.course_no = 'c001');
--正解
SELECT *
  FROM (SELECT *
          FROM hand_student_core core1
         WHERE core1.course_no = 'c001') t1
  JOIN (SELECT *
          FROM hand_student_core core1
         WHERE core1.course_no = 'c002') t2
    ON t1.student_no = t2.student_no
 WHERE t1.core > t2.core;


--4.	按各科平均成绩和及格率的百分数，按及格率高到低的顺序排序，显示（课程号、平均分、及格率）
--方法一：
WITH aa AS
 (SELECT c.course_no,
         AVG(c.core) avg1,
         COUNT(*) num1
    FROM hand_student_core c
   GROUP BY c.course_no),
bb AS
 (SELECT c2.course_no,
         COUNT(*) count1
    FROM hand_student_core c2
   WHERE c2.core >= 60
   GROUP BY c2.course_no)
SELECT aa.course_no, aa.avg1, nvl2(bb.count1 / aa.num1, bb.count1 / aa.num1, 0)
  FROM aa
  LEFT JOIN bb
    ON aa.course_no = bb.course_no
 ORDER BY nvl2(bb.count1 / aa.num1, bb.count1 / aa.num1, 0) DESC;
 
--方法二：（优先使用）
SELECT core1.course_no,
       AVG(core1.core),
       COUNT(CASE
               WHEN core1.core >= 60 THEN
                'X'
             END) / COUNT(*) rate
  FROM hand_student_core core1
 GROUP BY core1.course_no order by rate desc;

--5.	1992年之后出生的学生名单找出年龄最大和最小的同学，显示（学号、姓名、年龄）
--方法一：
WITH maxage AS
 (SELECT MAX(stu.student_age)
    FROM hand_student stu
   WHERE 2018 - stu.student_age > 1992),
minage AS
 (SELECT MIN(stu.student_age)
    FROM hand_student stu
   WHERE 2018 - stu.student_age > 1992)
SELECT s.student_no,s.student_name,s.student_age
  FROM hand_student s
 WHERE s.student_age = (SELECT *
                             FROM maxage) OR s.student_age = (SELECT *
                                                                   FROM minage);
--方法二：（答案）
SELECT hs.student_no,
       hs.student_name,
       hs.student_age
  FROM hand_student hs,
       (SELECT MAX(hs.student_age) max_age, 
               MIN(hs.student_age) min_age
          FROM hand_student hs
         WHERE to_number(to_char(SYSDATE, 'yyyy')) - hs.student_age > 1992) hh
 WHERE hs.student_age = hh.max_age OR hs.student_age = hh.min_age;

--6.	统计列出矩阵类型各分数段人数，横轴为分数段[100-85]、[85-70]、[70-60]、[<60]，纵轴为课程号、课程名称（提示使用case when句式）
SELECT course.course_no,
       course.course_name,
       COUNT(CASE
               WHEN core1.core >= 85
                    AND core1.core < 100 THEN
                'X'
             END) "[100-85]",
       COUNT(CASE
               WHEN core1.core >= 70
                    AND core1.core < 85 THEN
                'X'
             END) "[85-70]",
       COUNT(CASE
               WHEN core1.core >= 60
                    AND core1.core < 70 THEN
                'X'
             END) "[70-60]",
       COUNT(CASE
               WHEN core1.core < 60 THEN
                'X'
             END) "[<60]"
  FROM hand_student_core core1
  JOIN hand_course course
    ON core1.course_no = course.course_no
 GROUP BY course.course_no,
          course.course_name;


--7.	查询各科成绩前三名的记录:(不考虑成绩并列情况)，显示（学号、课程号、分数）
SELECT *
  FROM (SELECT core1.student_no,
               core1.course_no,
               core1.core,
               row_number() over(PARTITION BY core1.course_no ORDER BY core1.core DESC) rn
          FROM hand_student_core core1) t
 WHERE t.rn <= 3;
                


--8.	查询选修“谌燕”老师所授课程的学生中每科成绩最高的学生，显示（学号、姓名、课程名称、成绩）
--方法一：
SELECT t.student_no,
       t.student_name,
       t.course_name,
       t.core
  FROM (SELECT stu.student_no,
               stu.student_name,
               course.course_name,
               core1.core,
               dense_rank() over(PARTITION BY core1.course_no ORDER BY core1.core DESC) rn
          FROM hand_student_core core1
          JOIN hand_student stu
            ON core1.student_no = stu.student_no
          JOIN hand_course course
            ON core1.course_no = course.course_no
         WHERE course.teacher_no IN (SELECT tea2.teacher_no
                                       FROM hand_teacher tea2
                                      WHERE tea2.teacher_name = '谌燕')) t
 WHERE t.rn = 1;
 --方法二：（答案）
 SELECT hs.student_no,
        hs.student_name,
        hc.course_name,
        hsc.core
   FROM hand_student      hs,
        hand_student_core hsc,
        hand_course       hc,
        hand_teacher      ht
  WHERE hs.student_no = hsc.student_no
    AND hsc.course_no = hc.course_no
    AND hc.teacher_no = ht.teacher_no
    AND ht.teacher_name = '谌燕'
    AND hsc.core = (SELECT MAX(sc.core)
                      FROM hand_student_core sc
                     WHERE sc.course_no = hc.course_no);
                     
--方法三：（优先使用）
SELECT core1.student_no,
       core1.course_no,
       core1.core
  FROM hand_student_core core1
  JOIN hand_course course
    ON core1.course_no = course.course_no
  JOIN hand_teacher tea
    ON course.teacher_no = tea.teacher_no
 WHERE core1.core = (SELECT MAX(core2.core)
                       FROM hand_student_core core2
                      WHERE core1.course_no = core2.course_no)
   AND tea.teacher_name = '谌燕';


--9.	查询两门以上不及格课程的同学及平均成绩，显示（学号、姓名、平均成绩（保留两位小数））
--方法一：
WITH aa AS
 (SELECT c.student_no
    FROM hand_student_core c
   WHERE c.core < 60
   GROUP BY c.student_no
  HAVING COUNT(*) >= 2)
SELECT c.student_no, stu.student_name, AVG(c.core)
  FROM hand_student_core c
  JOIN hand_student stu
    ON c.student_no = stu.student_no
 WHERE c.student_no IN (
SELECT *
  FROM aa)
 GROUP BY c.student_no,stu.student_name;
 
 --方法二：（答案）
 SELECT hsc.student_no, 
       hs.student_name,
       ROUND(AVG(hsc.core),2) avg_core
  FROM hand_student_core hsc,
       hand_student hs
 WHERE EXISTS (SELECT sc.student_no
                 FROM hand_student_core sc
                WHERE sc.core < 60
                  AND sc.student_no = hsc.student_no
                GROUP BY sc.student_no
               HAVING COUNT(sc.student_no) > 1)
   AND hsc.student_no = hs.student_no
 GROUP BY hsc.student_no,hs.student_name;
--方法三：（不完整）
SELECT distinct(core1.student_no)
  FROM hand_student_core core1
 WHERE 2 <= (SELECT COUNT(1)
          FROM hand_student_core core2
         WHERE core1.student_no = core2.student_no
           AND core2.core < 60);

--10.	查询姓氏数量最多的学生名单，显示（学号、姓名、人数）
--方法一：
SELECT *
  FROM hand_student s
 WHERE substr(s.student_name,
              1,
              1) = (SELECT t.name1
                      FROM (SELECT substr(stu.student_name,
                                          1,
                                          1) name1,
                                   COUNT(*)
                              FROM hand_student stu
                             GROUP BY substr(stu.student_name,
                                             1,
                                             1)
                             ORDER BY COUNT(*) DESC) t
                     WHERE rownum = 1);
--方法二：（优先使用）
SELECT *
  FROM hand_student s
 WHERE substr(s.student_name,
              1,
              1) in (SELECT t.name1
                      FROM (SELECT substr(stu.student_name,
                                          1,
                                          1) name1,
                                   COUNT(*),
                                   dense_rank() OVER(ORDER BY COUNT(*) DESC) ranks
                              FROM hand_student stu
                             GROUP BY substr(stu.student_name,
                                             1,
                                             1)
                             )t where t.ranks=1);
               

--11.	查询课程名称为“J2SE”的学生成绩信息，90以上为“优秀”、80-90为“良好”、60-80为“及格”、60分以下为“不及格”，显示（学号、姓名、课程名称、成绩、等级）
SELECT stu.student_no,
       stu.student_name,
       course.course_name,
       CASE
         WHEN core1.core > 90 THEN
          '优秀'
         WHEN core1.core > 80 THEN
          '良好'
         WHEN core1.core > 60 THEN
          '及格'
         WHEN core1.core < 60 THEN
          '不及格'
       END
  FROM hand_student_core core1
  JOIN hand_student stu
    ON core1.student_no = stu.student_no
  JOIN hand_course course
    ON core1.course_no = course.course_no
 WHERE course.course_name = 'J2SE';

--12.	这是一个树结构，查询教师“胡明星”的所有主管及姓名:（无主管的教师也需要显示），显示（教师编号、教师名称、主管编号、主管名称）
WITH aa AS
 (SELECT *
    FROM hand_teacher tea
   START WITH tea.teacher_name = '胡明星'
  CONNECT BY PRIOR tea.manager_no = tea.teacher_no)
SELECT aa.teacher_no, aa.teacher_name, aa.manager_no, t.teacher_no
  FROM aa
  LEFT JOIN hand_teacher t
    ON aa.manager_no = t.teacher_no;

--13.	查询分数高于课程“J2SE”中所有学生成绩的学生课程信息，显示（学号，姓名，课程名称、分数）
SELECT stu.student_no,
       stu.student_name,
       course.course_name,
       core2.core
  FROM hand_student_core core2
  JOIN hand_student stu
    ON core2.student_no = stu.student_no
  JOIN hand_course course
    ON core2.course_no = course.course_no
 WHERE core2.core > (SELECT MAX(core1.core)
                       FROM hand_student_core core1
                      WHERE core1.course_no = (SELECT course.course_no
                                                 FROM hand_course course
                                                WHERE course.course_name = 'J2SE'));


--14.	分别根据教师、课程、教师和课程三个条件统计选课的学生数量：（使用rollup),显示（教师名称、课程名称、选课数量）
SELECT tea.teacher_name,
       course.course_name,
       COUNT(*)
  FROM hand_student_core core1
  JOIN hand_course course
    ON core1.course_no = course.course_no
  JOIN hand_teacher tea
    ON course.teacher_no = tea.teacher_no
 GROUP BY ROLLUP(tea.teacher_name,
                 course.course_name);
                 

--15.	查询所有课程成绩前三名的按照升序排在最开头，其余数据排序保持默认（7分）,显示（学号、成绩）
--测试
SELECT *
  FROM (SELECT core1.student_no,
               core1.course_no,
               core1.core,
               row_number() over(PARTITION BY core1.course_no ORDER BY core1.core DESC) rn
          FROM hand_student_core core1) t where rn =3;       
--正解
 SELECT *
   FROM (SELECT HSC.STUDENT_NO,
                HSC.COURSE_NO,
                HSC.CORE,
                ROW_NUMBER() OVER(PARTITION BY HSC.COURSE_NO ORDER BY HSC.CORE DESC) RANKS
           FROM HAND_STUDENT_CORE HSC) HS
  WHERE RANKS <= 3
UNION ALL
 SELECT *
   FROM (SELECT HSC.STUDENT_NO,
                HSC.COURSE_NO,
                HSC.CORE,
                ROW_NUMBER() OVER(PARTITION BY HSC.COURSE_NO ORDER BY HSC.CORE DESC) RANKS
           FROM HAND_STUDENT_CORE HSC) HS
  WHERE RANKS > 3