https://www.cnblogs.com/pingliangren/p/5586918.html
查询student表的第2条到4条记录详解：
https://blog.csdn.net/superit401/article/details/51036283
查询语句：
#学生表
CREATE TABLE student
(
Id int(10) NOT NULL UNIQUE PRIMARY KEY AUTO_INCREMENT,
Name varchar(20) NOT NULL,
Sex varchar(4),
Birth YEAR,
Department varchar(20) NOT NULL,
Address varchar(50)
)
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');
#成绩表
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)
)
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);
#1.查询student表的所有记录
SELECT * FROM student
#2.查询student表的第2条到4条记录
SELECT * FROM student LIMIT 1,3
#3.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 student
#4.一、从student表中查询计算机系和英语系的学生的信息
SELECT *
FROM student
WHERE Department = '计算机系' OR department = '英语系'
#4.二、从student表中查询计算机系和英语系的学生的信息
SELECT *
FROM student
WHERE Department IN('计算机系','英语系')
#5.从student表中查询年龄28~30岁的学生信息
SELECT Id,Name,Sex,2019-Birth AS age,Department,Address
FROM student
WHERE 2019-Birth BETWEEN 28 AND 30
#6.从student表中查询每个院系有多少人
#PS:可以用COUNT(Name)代替，但前提是不同名。Id是唯一性的
SELECT department,COUNT(Id)
FROM student
GROUP BY department
#7.从score表中查询每个科目的最高分
SELECT C_name,MAX(Grade)
FROM score
GROUP BY C_name
#8.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 student
WHERE Name = '李四')
#9.用连接的方式查询所有学生的信息和考试信息
SELECT *
FROM student,score
WHERE student.Id = score.Stu_id
#10.计算每个学生的总成绩
SELECT Stu_id,SUM(Grade)
FROM score
GROUP BY Stu_id
#11.计算每个考试科目的平均成绩
SELECT C_name,AVG(Grade)
FROM score
GROUP BY C_name
#12.查询计算机成绩低于95的学生信息
SELECT *
FROM student
WHERE Id =
ANY (SELECT Stu_id
FROM score
WHERE C_name = '计算机' AND Grade < 95)
#13.查询同时参加计算机和英语考试的学生的信息
#PS:计算机和英语位置可互换
SELECT *
FROM student
WHERE Id =
ANY (SELECT Stu_id FROM score
WHERE Stu_id =
ANY (SELECT Stu_id
FROM score
WHERE C_name = '计算机') AND C_name = '英语')
#14.将计算机考试成绩按从高到低进行排序
SELECT Stu_id,Grade
FROM score
WHERE C_name = '计算机'
ORDER BY Grade
#15.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 student
UNION SELECT Stu_id FROM score
#16.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 Name,Department,C_name,Grade
FROM student,score
WHERE (Name LIKE '张%' OR Name LIKE '王%') AND student.Id = score.Stu_id
#17.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,2019-Birth AS age,Department,C_name,Grade
FROM student,score
WHERE (Address LIKE '湖南%') AND student.Id = score.Stu_id
#18.查询出中文成绩高于计算机成绩的学员信息
SELECT