MySQL笔试

4. 查询student表的第2条到4条记录

SELECT * FROM stu_info LIMIT 1,3;

5.从student表查询所有学生的学号（id）、姓名（name）和院系（department）的信息

SELECT id,`name`,Department FROM stu_info;

7.从student表中查询年龄18~22岁的学生信息

SELECT * FROM stu_info WHERE 2010-Brith>18 AND 2010-Brith<22;

SELECT * FROM stu_info WHERE 2010-Brith BETWEEN 18 AND 22;

8.从student表中查询每个院系有多少人

SELECT department,COUNT(id) from stu_info GROUP BY Department;

(SELECT department AS 院系,COUNT(id) AS 人数 from stu_info GROUP BY Department;)

9.从score表中查询每个科目的最高分

SELECT c_name AS 科目,MAX(Grade) AS 最高分 FROM score GROUP BY c_name;

10.查询李四的考试科目（c_name）和考试成绩（grade）

select c_name,grade from score where stu_id=(SELECT id FROM stu_info where name='李四');

SELELCT score.c_name,score.grade FROM stu_info,score WHERE
stu_info.id = score.stu_id AND stu_info.name = '李四';

11.用连接的方式查询所有学生的信息和考试信息

SELECT * FROM stu_info,score WHERE(stu_info.id=score.stu_id);

SELECT * FROM stu_info INNER JOIN score ON stu_info.id=score.stu_id;

12.计算每个学生的总成绩

select stu_id as 学号,SUM(Grade) as 总成绩 from score GROUP BY stu_id;

select stu_info.name,SUM(Grade) from stu_info,score WHERE
stu_info.id = score.stu_id GROUP BY stu_info.id;

13.计算每个考试科目的平均成绩
SELECT c_name,AVG(grade) from score GROUP BY c_name;

14.查询计算机成绩低于95的学生信息

SELECT * from stu_info WHERE id in(select stu_id from score WHERE Grade < 95 AND c_name='计算机');

15.查询同时参加计算机和英语考试的学生的信息

SELECT DISTINCT name,stu.id FROM student stu,score sc ,score sc1 WHERE stu.id=sc.stu_id AND sc.c_name='计算机' AND sc1.c_name='英语';

SELECT * FROM student WHERE id IN ( SELECT stu_id FROM score WHERE stu_id IN (SELECT stu_id FROM score WHERE c_name= '计算机') AND c_name= '英语' );

16.将计算机考试成绩按从高到低进行排序
select c_name,Grade from score where c_name='计算机' order by Grade DESC;

select c_name,Grade from score order by Grade DESC HAVING c_name='计算机';

17.从student表和score表中查询出学生的学号，然后合并查询结果
select id from stu_info union select stu_id from score;

18.查询姓张或者姓王的同学的姓名、院系和考试科目及成绩

select stu_id.name stu_id.department,score.c_name,score.grade from stu_info,score
where stu_info.id = score.stu_id AND (stu_info.name LIKE '张%'or stu_info.name LIKE "王%");

19.查询都是湖南的学生的姓名、年龄、院系和考试科目及成绩

SELECT `name`,2010-Brith,Department,c_name,Grade FROM stu_info,score WHERE address LIKE '湖南%';

SELECT `name`,2010-Brith,Department,c_name,Grade,department FROM stu_info.score WHERE stu_info.id=score.stu_id AND student.address LIKE '湖南%'