50道经典SQL练习题和答案-1-10

50个常用sql语句

一，创建表

Student(SId,Sname,Sage,Ssex) 学生表
Course(CId,Cname,TId) 课程表
SC(SId,CId,score) 成绩表
Teacher(TId,Tname) 教师表

创建表
创建学生表Student

create table Student(SId varchar(10),Sname varchar(10),Sage Date,Ssex varchar(10));

创建科目表Course

create table Course(CId varchar(10),Cname varchar(10),TId varchar(10))；

创建教师表teacher

create table Teacher(TId varchar(10),Tname varchar(10))；

创建成绩表 SC

create table SC(SId varchar(10),CId varchar(10),score decimal(18,1));

插入数据

insert into Student values('01' , '赵雷' , '1990-01-01', '男');
insert into Student values('02' , '钱电' , '1990-12-21', '男');
insert into Student values('03' , '孙风' , '1990-05-20', '男');
insert into Student values('04' , '李云' , '1990-08-06', '男');
insert into Student values('05' , '周梅' , '1991-12-01', '女');
insert into Student values('06' , '吴兰' , '1992-03-01', '女');
insert into Student values('07' , '郑竹' , '1989-07-01', '女');
insert into Student values('09' , '张三' , '2017-12-20', '女');
insert into Student values('10' , '李四' , '2017-12-25', '女');
insert into Student values('11' , '李四' , '2017-12-30', '女');
insert into Student values('12' , '赵六' , '2017-01-01', '女');
insert into Student values('13' , '孙七' , '2018-01-01', '女');insert into Course values('01' , '语文' , '02');
insert into Course values('02' , '数学' , '01');
insert into Course values('03' , '英语' , '03');
insert into Course values('04' , '化学' , '04');insert into Teacher values('01' , '张三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');
insert into Teacher values('04' , '李明');insert into SC values('01' , '01' , 80);
insert into SC values('01' , '02' , 90);
insert into SC values('01' , '03' , 99);
insert into SC values('01' , '04' , 88);
insert into SC values('02' , '01' , 70);
insert into SC values('02' , '02' , 60);
insert into SC values('02' , '03' , 80);
insert into SC values('03' , '01' , 80);
insert into SC values('03' , '02' , 80);
insert into SC values('03' , '03' , 77);
insert into SC values('03' , '04' , 80);
insert into SC values('04' , '01' , 50);
insert into SC values('04' , '02' , 30);
insert into SC values('04' , '03' , 20);
insert into SC values('05' , '01' , 76);
insert into SC values('05' , '02' , 87);
insert into SC values('05' , '04' , 75);
insert into SC values('06' , '01' , 31);
insert into SC values('06' , '03' , 34);
insert into SC values('07' , '02' , 89);
insert into SC values('07' , '03' , 98);

1、查询“01”课程比“02”课程成绩高的所有学生的学号;

 SELECT a.SId FROM(SELECT SId,score FROM sc where CId=01)as a,(SELECT SId,score FROM sc where CId=02)as bwhere a.SId=b.SId AND a.score > b.score

查询结果

2、查询平均成绩大于60分的同学的学号和平均成绩;

SELECT SId,AVG(score) from sc GROUP BY SId HAVING AVG(score)>60;

3、查询所有同学的学号、姓名、选课数、总成绩;

SELECTs.SId as 学号,s.Sname as 姓名,count(c.CId) as 选课数,SUM(c.score) as 总分
FROMstudent s
LEFT OUTER JOIN sc c ON s.SId = c.SId
GROUP BYs.SId
HAVINGSUM(CId)

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“李明”老师课的同学的学号、姓名;

SELECT s.SId,s.Sname FROM student s WHERE s.SId NOT in (
SELECT sc.SId FROM sc,course,teacher where sc.CId=course.CId AND course.TId=teacher.TId AND teacher.Tname="李明");

6、查询学过“01”并且也学过编号“02”课程的同学的学号、姓名;

SELECTs.SId,s.Sname
FROMstudent s,sc c
WHEREs.SId = c.SId
AND c.CId = 01 AND EXISTS (SELECT*FROMsc c_2WHEREc.SId = c_2.SIdAND c_2.CId = 02
)

7、查询学过“李明”老师所教的所有课的同学的学号、姓名;

SELECTs.SId,s.Sname
FROMstudent s
JOIN sc c ON s.SId = c.SId
JOIN course c_2 ON c.CId = c_2.CId
JOIN teacher t ON t.TId = c_2.TId
AND t.Tname = '李明'

8、查询课程编号“02”的成绩比课程编号“01”课程低的所有同学的学号、姓名;

SELECT SId,Sname FROM(SELECT student.SId,student.Sname,score,(SELECT score FROM sc SC_2 WHERE SC_2.SId = student.SId AND SC_2.CId = '02' )score2 FROM student, scWHERE student.SId = SC.SIdAND CId = '01')s_2
WHEREscore2  < score;

9、查询所有课程成绩小于60分的同学的学号、姓名;

SELECT s.SId,s.Sname FROM student s
WHERE SId NOT IN(SELECT student.SId FROM student,sc WHERE student.SId=sc.SId AND score>60);

10、查询没有学全所有课的同学的学号、姓名;

SELECT s.SId,s.Sname FROM student s,sc c
WHERE s.SId=c.SId GROUP BY s.SId,s.Sname HAVING COUNT(CId) < (SELECT COUNT(CId) FROM course)

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50道经典SQL练习题和答案-1-10

50个常用sql语句

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