create database one20210611 default charset=utf8;
use one20210611;
CREATE TABLE `studentinfo` (
`StudentID` char(10) DEFAULT NULL,
`StudentName` varchar(20) DEFAULT NULL,
`Gender` varchar(2) DEFAULT NULL,
`Birthday` date DEFAULT NULL,
`ClassID` int(4) DEFAULT NULL,
`BeginYear` year(4) DEFAULT NULL,
`Phone` varchar(11) DEFAULT NULL,
`Province` varchar(20) DEFAULT NULL,
`City` varchar(20) DEFAULT NULL,
`Email` varchar(50) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
create table teacher (
id int,
teachername VARCHAR(10),
hiredate DATE,
gender char
);
create table classinfo (
id int, # 班级编号
classname varchar(10),
gradeid int, # 年级编号
beginyear varchar(10) # 开始年份
);
create table subject (
id int ,
subjectname varchar(10),
teacherid int
);
create table exam (
id int,
exam int,
subjectid int,
studentid int,
remark varchar(10) # 备注
);
create table grade(
id int ,
gradename varchar(10),
major varchar(20)
);
INSERT INTO `one20210611`.`classinfo`(`id`, `classname`, `gradeid`, `beginyear`) VALUES (2001, '20级1班', 20, '2020');
INSERT INTO `one20210611`.`classinfo`(`id`, `classname`, `gradeid`, `beginyear`) VALUES (2002, '20级2班', 20, '2020');
INSERT INTO `one20210611`.`exam`(`id`, `exam`, `subjectid`, `studentid`, `remark`) VALUES (1, 98, 101, 1, '无');
INSERT INTO `one20210611`.`exam`(`id`, `exam`, `subjectid`, `studentid`, `remark`) VALUES (2, 89, 102, 1, NULL);
INSERT INTO `one20210611`.`exam`(`id`, `exam`, `subjectid`, `studentid`, `remark`) VALUES (3, 79, 103, 1, '');
INSERT INTO `one20210611`.`exam`(`id`, `exam`, `subjectid`, `studentid`, `remark`) VALUES (4, 96, 104, 1, NULL);
INSERT INTO `one20210611`.`exam`(`id`, `exam`, `subjectid`, `studentid`, `remark`) VALUES (5, 85, 101, 2, NULL);
INSERT INTO `one20210611`.`exam`(`id`, `exam`, `subjectid`, `studentid`, `remark`) VALUES (6, 89, 102, 2, NULL);
INSERT INTO `one20210611`.`exam`(`id`, `exam`, `subjectid`, `studentid`, `remark`) VALUES (7, 79, 103, 2, NULL);
INSERT INTO `one20210611`.`exam`(`id`, `exam`, `subjectid`, `studentid`, `remark`) VALUES (8, 83, 104, 2, NULL);
INSERT INTO `one20210611`.`grade`(`id`, `gradename`, `major`) VALUES (20, '20级', '软件技术');
INSERT INTO `one20210611`.`studentinfo`(`StudentID`, `StudentName`, `Gender`, `Birthday`, `ClassID`, `BeginYear`, `Phone`, `Province`, `City`, `Email`) VALUES ('1', '张无忌', '男', '2021-06-10', 2001, 2020, '13012340001', '河南', '许昌', '[email protected]');
INSERT INTO `one20210611`.`studentinfo`(`StudentID`, `StudentName`, `Gender`, `Birthday`, `ClassID`, `BeginYear`, `Phone`, `Province`, `City`, `Email`) VALUES ('2', '张铁牛', '男', '2021-06-16', 2001, 2020, '13012340002', '河南', '许昌', '[email protected]');
INSERT INTO `one20210611`.`studentinfo`(`StudentID`, `StudentName`, `Gender`, `Birthday`, `ClassID`, `BeginYear`, `Phone`, `Province`, `City`, `Email`) VALUES ('3', '林平之', '男', '2021-06-15', 2001, 2020, '13012340003', '河南', '安阳', '[email protected]');
INSERT INTO `one20210611`.`studentinfo`(`StudentID`, `StudentName`, `Gender`, `Birthday`, `ClassID`, `BeginYear`, `Phone`, `Province`, `City`, `Email`) VALUES ('4', '令狐冲', '男', '2021-06-08', 2002, 2019, '13012340004', '河南', '濮阳', '[email protected]');
INSERT INTO `one20210611`.`studentinfo`(`StudentID`, `StudentName`, `Gender`, `Birthday`, `ClassID`, `BeginYear`, `Phone`, `Province`, `City`, `Email`) VALUES ('5', '岳灵珊', '女', '2021-06-02', 2002, 2019, '13012340005', '河南', '南阳', '[email protected]');
INSERT INTO `one20210611`.`subject`(`id`, `subjectname`, `teacherid`) VALUES (101, 'mysql', 201);
INSERT INTO `one20210611`.`subject`(`id`, `subjectname`, `teacherid`) VALUES (102, 'java基础', 201);
INSERT INTO `one20210611`.`subject`(`id`, `subjectname`, `teacherid`) VALUES (103, '面向对象', 202);
INSERT INTO `one20210611`.`subject`(`id`, `subjectname`, `teacherid`) VALUES (104, '网页设计', 202);
INSERT INTO `one20210611`.`teacher`(`id`, `teachername`, `hiredate`, `gender`) VALUES (201, 'hys', '2021-06-04', '男');
INSERT INTO `one20210611`.`teacher`(`id`, `teachername`, `hiredate`, `gender`) VALUES (202, 'dj', '2021-06-01', '女');
-- 子查询 用子查询实现，查询出学生“林平之”的同班同学 '
-- 1 查出林平之的班级
select classid from studentinfo where studentname='林平之';
-- 2 根据班级查询同班学生信息
select * from studentinfo where classid=2001;
-- 合并
select * from studentinfo where classid=(select classid from studentinfo where studentname='林平之');
-- 查询《mysql》考试成绩刚好等于85分的学生名单
-- 1 需要查询学生名单 在studentinfo
-- 2 科目是mysql 在subject表中 id
-- 3 成绩为90 在exam表中subjectid studentid
select studentname from studentinfo inner join exam on studentinfo.StudentID=exam.studentid inner join subject on subject.id=exam.subjectid
where subject.subjectname='mysql' and exam.exam=85;
select studentname from studentinfo, exam , `subject`
where studentinfo.StudentID=exam.studentid and subject.id=exam.subjectid and subject.subjectname='mysql' and exam.exam=85;
-- 查询《mysql》考试成绩刚好等于85分的学生名单 子查询
# 根据学生id查询学生的名单
select studentname from studentinfo where studentid = ?
# 在成绩中找到成绩为85的学生id
select studentid from exam where exam=85;
# 在课程表中找到mysql的课程id
select id from subject where subjectname='mysql' ;
-- 融合
select studentname from studentinfo where studentid = (select studentid from exam where exam=85 and subjectid = (select id from subject where subjectname='mysql' ) ) ;
-- 更新“dj”的“网页设计”成绩为+5分
-- 找到……成绩 +5 exam id subjectid studentid
update exam set exam = exam + 5 where subjectid = ?
-- 找到mysql课程的id subject id subjectname
select id from subject where subjectname = "网页设计"
-- 根据名字找id teacher
select id from teacher where teachername='dj'
-- 融合
update exam set exam = exam + 5 where subjectid = (select id from subject where subjectname = "网页设计" and subject.teacherid = (select id from teacher where teachername='dj' ))
-- 删除“张无忌”的所有考试成绩
-- 1 在studentinfo表中找到张无忌的学生id
select studentid from studentinfo where studentname="张无忌"
-- 2 根据id在exam表中删除成绩
delete from exam where studentid=?
-- 合并
delete from exam where studentid= (select studentid from studentinfo where studentname="张无忌");
-- 插入的子查询 把查询的结果作为内容 插入到新的数据
insert into studentinfo (select * from studentinfo where studentid=5)
-- 查询《mysql》考试成绩刚好等于85分的学生名单 in 的使用 在……范围之内
# 根据学生id查询学生的名单
select studentname from studentinfo where studentid = ?
# 在成绩中找到成绩为85的学生id
select studentid from exam where exam=85;
# 在课程表中找到mysql的课程id
select id from subject where subjectname='mysql' ;
-- 融合
select studentname from studentinfo where studentid in (select studentid from exam where exam=85 and subjectid in (select id from subject where subjectname='mysql' ) ) ;
-- 查询成绩表中科目编号为102的考试成绩中是否存在不及格的学生，如果存在不及格的学生就将参加科目编号102考试的学生编号和成绩全部查询显示出来
-- 是否存在不及格的学生
SELECT StudentID from EXAM WHERE Exam<60
-- 参加科目编号102考试的学生
WHERE SubjectID=102
-- 学生编号和成绩全部查询显示出来
SELECT StudentID,Exam FROM EXAM
-- 合并
SELECT StudentID,Exam FROM EXAM WHERE SubjectID=102 AND EXISTS (SELECT StudentID from EXAM WHERE Exam<60);
-- 查询成绩比科目编号为“101”的这门课程的所有成绩都大的学生考试信息
-- 1 查询……学生考试信息
SELECT * FROM Exam WHERE where ?
-- 2 成绩比科目编号为“101”的这门课程的所有成绩都大
all(SELECT Exam from EXAM WHERE SubjectID=101)
-- 合并
SELECT * FROM exam where exam > all(SELECT Exam from EXAM WHERE subjectid=101);
-- 查询成绩比科目编号为“101”的任意一个成绩都大的考试信息
-- 1 查询……学生考试信息
SELECT * FROM Exam WHERE where ?
-- 2 成绩比科目编号为“101”的这门课程的所有成绩都大
any(SELECT Exam from EXAM WHERE SubjectID=1)
-- 合并
SELECT * FROM exam where exam > any(SELECT Exam from EXAM WHERE subjectid=101);
SELECT * FROM exam where exam > some(SELECT Exam from EXAM WHERE subjectid=101);