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1.创建student和score表
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CREATE TABLE student ( id INT(10) NOT NULL UNIQUE PRIMARY KEY , name VARCHAR(20) NOT NULL , sex VARCHAR(4) , birth YEAR, department VARCHAR(20) , address VARCHAR(50) ); |
创建score表。SQL代码如下:
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CREATE TABLE score ( id INT(10) NOT NULL UNIQUE PRIMARY KEY AUTO_INCREMENT , stu_id INT(10) NOT NULL , c_name VARCHAR(20) , grade INT(10) ); |
2.为student表和score表增加记录
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向student表插入记录的INSERT语句如下: INSERT INTO student VALUES( 901,'张老大', '男',1985,'计算机系', '北京市海淀区'); INSERT INTO student VALUES( 902,'张老二', '男',1986,'中文系', '北京市昌平区'); INSERT INTO student VALUES( 903,'张三', '女',1990,'中文系', '湖南省永州市'); INSERT INTO student VALUES( 904,'李四', '男',1990,'英语系', '辽宁省阜新市'); INSERT INTO student VALUES( 905,'王五', '女',1991,'英语系', '福建省厦门市'); INSERT INTO student VALUES( 906,'王六', '男',1988,'计算机系', '湖南省衡阳市'); #向score表插入记录的INSERT语句如下: INSERT INTO score VALUES(NULL,901, '计算机',98); INSERT INTO score VALUES(NULL,901, '英语', 80); INSERT INTO score VALUES(NULL,902, '计算机',65); INSERT INTO score VALUES(NULL,902, '中文',88); INSERT INTO score VALUES(NULL,903, '中文',95); INSERT INTO score VALUES(NULL,904, '计算机',70); INSERT INTO score VALUES(NULL,904, '英语',92); INSERT INTO score VALUES(NULL,905, '英语',94); INSERT INTO score VALUES(NULL,906, '计算机',90); INSERT INTO score VALUES(NULL,906, '英语',85); |
3.查询student表的所有记录
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select * from student; |
4.查询student表的第2条到4条记录
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select * from student 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
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select id, name, department from student; |
6.从student表中查询计算机系和英语系的学生的信息
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select * from student where department = '计算机系' or department = '英语系'; |
7.从student表中查询年龄18~22岁的学生信息
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select * from student where birth between 1995 and 1999; |
8.从student表中查询每个院系有多少人
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select count(*) as num ,department from student GROUP BY department; |
9.从score表中查询每个科目的最高分
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select max(grade),c_name from score GROUP BY c_name; |
10.查询李四的考试科目(c_name)和考试成绩(grade)
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SELECT sc.c_name , sc.grade, st.name FROM student as st , score as sc where st.id = sc.stu_id and st.name = '李四'; |
11.查询所有学生的信息和考试信息
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SELECT * FROM student as st , score as sc where st.id = sc.stu_id; |
12.计算每个学生的总成绩
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SELECT st.name, SUM(sc.grade) FROM student as st , score as sc where st.id = sc.stu_id GROUP BY st.name; |
13.计算每个考试科目的平均成绩
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SELECT sc.c_name, avg(sc.grade) FROM student as st , score as sc where st.id = sc.stu_id GROUP BY sc.c_name; |
14.查询计算机成绩低于95的学生信息
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SELECT st.id, st.name, st.sex, st.department, st.address, sc.c_name, sc.grade FROM student as st , score as sc where st.id = sc.stu_id and sc.c_name = '计算机' and sc.grade < 95; |
15.查询同时参加计算机和英语考试的学生的信息
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SELECT * FROM student as st , score as sc where st.id = sc.stu_id and sc.c_name = '计算机' and st.id in (SELECT st.id FROM student as st , score as sc where st.id = sc.stu_id and sc.c_name = '英语'); |
16.将计算机考试成绩按从高到低进行排序
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SELECT sc.c_name, sc.grade FROM student as st , score as sc where st.id = sc.stu_id and sc.c_name = '计算机' ORDER BY sc.grade desc; |
17.从student表和score表中查询出学生的学号,然后合并查询结果
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SELECT distinct st.id FROM student as st , score as sc where st.id = sc.stu_id ; |
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
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SELECT st.name, st.department, sc.c_name, sc.grade FROM student as st , score as sc where st.id = sc.stu_id and st.name like '张%' or st.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
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SELECT st.name, st.birth, st.department, st.address, sc.c_name, sc.grade FROM student as st , score as sc where st.id = sc.stu_id and st.address like '湖南%'; |