sql语句面试题,关于多表连接

发布网友发布时间：2022-04-29 11:34

共3个回答

懂视网时间：2022-05-03 16:09

TABLE student ( s INT, sname varchar(32), sage INT, ssex varchar(8) ); CREATE TABLE course ( c INT, cname varchar(32), t INT ); CREATE TABLE sc ( s INT, c INT, score INT ); CREATE TABLE teacher ( t INT, tname varchar(16) )

插入测试数据语句【分表插入就不报错了】

 insert into Student select 1,N‘刘一‘,18,N‘男‘ union all
 select 2,N‘钱二‘,19,N‘女‘ union all
 select 3,N‘张三‘,17,N‘男‘ union all
 select 4,N‘李四‘,18,N‘女‘ union all
 select 5,N‘王五‘,17,N‘男‘ union all
 select 6,N‘赵六‘,19,N‘女‘ 
 
 insert into Teacher select 1,N‘叶平‘ union all
 select 2,N‘贺高‘ union all
 select 3,N‘杨艳‘ union all
 select 4,N‘周磊‘
 
 insert into Course select 1,N‘语文‘,1 union all
 select 2,N‘数学‘,2 union all
 select 3,N‘英语‘,3 union all
 select 4,N‘物理‘,4
 
 insert into SC 
 select 1,1,56 union all 
 select 1,2,78 union all 
 select 1,3,67 union all 
 select 1,4,58 union all 
 select 2,1,79 union all 
 select 2,2,81 union all 
 select 2,3,92 union all 
 select 2,4,68 union all 
 select 3,1,91 union all 
 select 3,2,47 union all 
 select 3,3,88 union all 
 select 3,4,56 union all 
 select 4,2,88 union all 
 select 4,3,90 union all 
 select 4,4,93 union all 
 select 5,1,46 union all 
 select 5,3,78 union all 
 select 5,4,53 union all 
 select 6,1,35 union all 
 select 6,2,68 union all 
 select 6,4,71

问题【报错的把#删掉就可以了】

问题： 
1、查询“001”课程比“002”课程成绩高的所有学生的学号； 
 select a.S# from (select s#,score from SC where C#=‘001‘) a,(select s#,score 
 from SC where C#=‘002‘) b 
 where a.score>b.score and a.s#=b.s#; 
2、查询平均成绩大于60分的同学的学号和平均成绩； 
 select S#,avg(score) 
 from sc 
 group by S# having avg(score) >60; 
3、查询所有同学的学号、姓名、选课数、总成绩； 
 select Student.S#,Student.Sname,count(SC.C#),sum(score) 
 from Student left Outer join SC on Student.S#=SC.S# 
 group by Student.S#,Sname 
4、查询姓“李”的老师的个数； 
 select count(distinct(Tname)) 
 from Teacher 
 where Tname like ‘李%‘; 
5、查询没学过“叶平”老师课的同学的学号、姓名； 
 select Student.S#,Student.Sname 
 from Student 
 where S# not in (select distinct( SC.S#) from SC,Course,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname=‘叶平‘); 
6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名； 
 select Student.S#,Student.Sname from Student,SC where Student.S#=SC.S# and SC.C#=‘001‘and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#=‘002‘); 
7、查询学过“叶平”老师所教的所有课的同学的学号、姓名； 
 select S#,Sname 
 from Student 
 where S# in (select S# from SC ,Course ,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname=‘叶平‘ group by S# having count(SC.C#)=(select count(C#) from Course,Teacher where Teacher.T#=Course.T# and Tname=‘叶平‘)); 
8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名； 
 Select S#,Sname from (select Student.S#,Student.Sname,score ,(select score from SC SC_2 where SC_2.S#=Student.S# and SC_2.C#=‘002‘) score2 
 from Student,SC where Student.S#=SC.S# and C#=‘001‘) S_2 where score2 <score; 
9、查询所有课程成绩小于60分的同学的学号、姓名； 
 select S#,Sname 
 from Student 
 where S# not in (select S.S# from Student AS S,SC where S.S#=SC.S# and score>60); 
10、查询没有学全所有课的同学的学号、姓名； 
 select Student.S#,Student.Sname 
 from Student,SC 
 where Student.S#=SC.S# group by Student.S#,Student.Sname having count(C#) <(select count(C#) from Course); 
11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名； 
 select distinct S#,Sname from Student,SC where Student.S#=SC.S# and SC.C# in (select C# from SC where S#=‘1001‘); 
12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名； 
 select distinct SC.S#,Sname 
 from Student,SC 
 where Student.S#=SC.S# and C# in (select C# from SC where S#=‘001‘); 
13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩； 
 update SC set score=(select avg(SC_2.score) 
 from SC SC_2 
 where SC_2.C#=SC.C# ) from Course,Teacher where Course.C#=SC.C# and Course.T#=Teacher.T# and Teacher.Tname=‘叶平‘); 
14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名； 
 select S# from SC where C# in (select C# from SC where S#=‘1002‘) 
 group by S# having count(*)=(select count(*) from SC where S#=‘1002‘); 
15、删除学习“叶平”老师课的SC表记录； 
 Delect SC 
 from course ,Teacher 
 where Course.C#=SC.C# and Course.T#= Teacher.T# and Tname=‘叶平‘; 
16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、2、 
 号课的平均成绩； 
 Insert SC select S#,‘002‘,(Select avg(score) 
 from SC where C#=‘002‘) from Student where S# not in (Select S# from SC where C#=‘002‘); 
17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分 
 SELECT S# as 学生ID 
 ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#=‘004‘) AS 数据库 
 ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#=‘001‘) AS 企业管理 
 ,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#=‘006‘) AS 英语 
 ,COUNT(*) AS 有效课程数, AVG(t.score) AS 平均成绩 
 FROM SC AS t 
 GROUP BY S# 
 ORDER BY avg(t.score) 
18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分 
 SELECT L.C# As 课程ID,L.score AS 最高分,R.score AS 最低分 
 FROM SC L ,SC AS R 
 WHERE L.C# = R.C# and 
 L.score = (SELECT MAX(IL.score) 
   FROM SC AS IL,Student AS IM 
   WHERE L.C# = IL.C# and IM.S#=IL.S# 
   GROUP BY IL.C#) 
 AND 
 R.Score = (SELECT MIN(IR.score) 
   FROM SC AS IR 
   WHERE R.C# = IR.C# 
   GROUP BY IR.C# 
   ); 自己写的:select c# ,max(score)as 最高分 ,min(score) as 最低分 from dbo.sc group by c#
19、按各科平均成绩从低到高和及格率的百分数从高到低顺序 
 SELECT t.C# AS 课程号,max(course.Cname)AS 课程名,isnull(AVG(score),0) AS 平均成绩 
 ,100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) AS 及格百分数 
 FROM SC T,Course 
 where t.C#=course.C# 
 GROUP BY t.C# 
 ORDER BY 100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) DESC 
20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 企业管理（001），马克思（002），OO&UML （003），数据库（004） 
 SELECT SUM(CASE WHEN C# =‘001‘ THEN score ELSE 0 END)/SUM(CASE C# WHEN ‘001‘ THEN 1 ELSE 0 END) AS 企业管理平均分 
 ,100 * SUM(CASE WHEN C# = ‘001‘ AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = ‘001‘ THEN 1 ELSE 0 END) AS 企业管理及格百分数 
 ,SUM(CASE WHEN C# = ‘002‘ THEN score ELSE 0 END)/SUM(CASE C# WHEN ‘002‘ THEN 1 ELSE 0 END) AS 马克思平均分 
 ,100 * SUM(CASE WHEN C# = ‘002‘ AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = ‘002‘ THEN 1 ELSE 0 END) AS 马克思及格百分数 
 ,SUM(CASE WHEN C# = ‘003‘ THEN score ELSE 0 END)/SUM(CASE C# WHEN ‘003‘ THEN 1 ELSE 0 END) AS UML平均分 
 ,100 * SUM(CASE WHEN C# = ‘003‘ AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = ‘003‘ THEN 1 ELSE 0 END) AS UML及格百分数 
 ,SUM(CASE WHEN C# = ‘004‘ THEN score ELSE 0 END)/SUM(CASE C# WHEN ‘004‘ THEN 1 ELSE 0 END) AS 数据库平均分 
 ,100 * SUM(CASE WHEN C# = ‘004‘ AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = ‘004‘ THEN 1 ELSE 0 END) AS 数据库及格百分数 
 FROM SC

21、查询不同老师所教不同课程平均分从高到低显示 
 SELECT max(Z.T#) AS 教师ID,MAX(Z.Tname) AS 教师姓名,C.C# AS 课程ＩＤ,MAX(C.Cname) AS 课程名称,AVG(Score) AS 平均成绩 
 FROM SC AS T,Course AS C ,Teacher AS Z 
 where T.C#=C.C# and C.T#=Z.T# 
 GROUP BY C.C# 
 ORDER BY AVG(Score) DESC 
22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），UML （003），数据库（004） 
 [学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩 
 SELECT DISTINCT top 3 
 SC.S# As 学生学号, 
 Student.Sname AS 学生姓名 , 
 T1.score AS 企业管理, 
 T2.score AS 马克思, 
 T3.score AS UML, 
 T4.score AS 数据库, 
 ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分 
 FROM Student,SC LEFT JOIN SC AS T1 
   ON SC.S# = T1.S# AND T1.C# = ‘001‘ 
  LEFT JOIN SC AS T2 
   ON SC.S# = T2.S# AND T2.C# = ‘002‘ 
  LEFT JOIN SC AS T3 
   ON SC.S# = T3.S# AND T3.C# = ‘003‘ 
  LEFT JOIN SC AS T4 
   ON SC.S# = T4.S# AND T4.C# = ‘004‘ 
 WHERE student.S#=SC.S# and 
 ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) 
 NOT IN 
 (SELECT 
  DISTINCT 
  TOP 15 WITH TIES 
  ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) 
 FROM sc 
  LEFT JOIN sc AS T1 
   ON sc.S# = T1.S# AND T1.C# = ‘k1‘ 
  LEFT JOIN sc AS T2 
   ON sc.S# = T2.S# AND T2.C# = ‘k2‘ 
  LEFT JOIN sc AS T3 
   ON sc.S# = T3.S# AND T3.C# = ‘k3‘ 
  LEFT JOIN sc AS T4 
   ON sc.S# = T4.S# AND T4.C# = ‘k4‘ 
 ORDER BY ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DESC); 

23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60] 
 SELECT SC.C# as 课程ID, Cname as 课程名称 
 ,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85] 
 ,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70] 
 ,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60] 
 ,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS [60 -] 
 FROM SC,Course 
 
 var cpro_id = "u6292429";
 



                                        
                        
                        热心网友
                        时间：2022-05-03 13:17
                    
                    比如学生表，有学号，姓名，年龄，性别这四个字段
select a.学号,a.姓名,a.年龄,a.性别,sum(c.成绩) as 总成绩
from 学生表 a,成绩表 b,选课表 c 
where a.学号=b.学号
and b.课程号=c.课程号
group by a.学号,a.姓名,a.年龄,a.性别
order by a.姓名 asc,sum(c.成绩) desc                    
                                                            

                        
                        热心网友
                        时间：2022-05-03 14:35
                    
                    order by 学生姓名,总成绩 desc
额 这里只回答了排序问题，你是想要这个么？