用root賬號管理其他用戶

#創建用戶

mysql> create user 'jasonhz'@'localhost' identified by '123456';

#給用戶授權

mysql> grant all privileges on myschool.* to 'jasonhz'@'localhost';

#刷新授權

mysql> flush privileges;

#更改用戶密碼

mysql> set password for 'jasonhz'@'localhost' = password('111222');

#刪除用戶

mysql> drop user 'jasonhz'@'localhost';

SQL語句(Structured Query Language 結構化查詢語言)

DDL (Data Definition Language 數據定義語言) 如：CREATE DROP ALTER

DML( Data Manipulation Language 數據操縱語言) 如： INSERT UPDATE DELETE

DQL(Data Query Language 數據查詢語言) 如：SELECT

DCL(Data Control Language 數據庫控制語言) 如：GRANT COMMIT ROLLBACK

DDL (Data Definition Language 數據庫定義語言)

#創建數據庫

mysql> create database if not exists hzdb;

#使用數據庫

mysql> use hzdb;

#查看所有可訪問的數據庫

#除了hzdb是自己創建的，mysql系統中有四個默認的庫 information_schema 、 mysql、performance_schema、sys

mysql> show databases;

+--------------------+

| Database |

+--------------------+

| information_schema |

| hzdb |

| mysql |

| performance_schema |

| sys |

+--------------------+

#刪除數據庫

mysql> drop database hzdb;

#查看數據庫支持的引擎

mysql> show engines;

#查看數據庫默認的引擎

mysql> show variables like '%storage_engine%';

#查看當前數據庫的編碼

mysql> show variables like '%char%';

#創建表

mysql> create table person(

-> `id` int(4) primary key auto_increment comment '編號',

-> `name` varchar(50) not null default '無名氏' comment '姓名',

-> `address` varchar(100) comment '地址'

-> )engine=innodb default charset=utf8 comment='人員信息';

#查看所有表

mysql> show tables;

#查看表的結構

mysql> desc person;

+---------+--------------+------+-----+-----------+----------------+

| Field | Type | Null | Key | Default | Extra |

+---------+--------------+------+-----+-----------+----------------+

| id | int(4) | NO | PRI | NULL | auto_increment |

| name | varchar(50) | NO | | 無名氏 | |

| address | varchar(100) | YES | | NULL | |

+---------+--------------+------+-----+-----------+----------------+

#修改表名

mysql> alter table person rename student;

#添加字段

mysql> alter table student add `phone` varchar(13) comment '電話';

#修改字段屬性，不能修改表名

mysql> alter table student modify `phone` int(11);

#修改字段，同時修改表名

mysql> alter table student change `phone` `tel` varchar(50) not null;

#刪除字段

mysql> alter table student drop `tel`;

#刪除表，刪除數據要慎重

mysql> drop table student;

DML( Data Manipulation Language 數據操縱語言)

#添加數據

mysql> insert into student (`id`,`name`) values ('1','張三');

mysql> insert into student (`id`,`name`) values ('4','張三'),('6','李四'),('8','王五');

#修改數據

mysql> update student set `name`='李靖' where id=1;

#刪除數據

mysql> delete from student where id=1;

#刪除所有數據，兩種方法

mysql> delete from student;

mysql> truncate table student;

DQL(Data Query Language 數據查詢語言)

(有需要sql腳本做練習的請聯系我)

#基本查詢：

#查詢student表中全部信息

mysql> select * from student;

#通過student表，查詢`studentNo`,`studentName`,`phone`,`address`,`birthday`字段的信息

mysql> select studentNo, studentName, phone, address, birthday from student;

#通過student表，查詢`studentNo`,`studentName`,`phone`,`address`,`birthday`字段的信息，使用as重命名列名顯示

mysql> select studentNo as 學號,studentName as 姓名,phone as 電話,address as 地址,birthday as 生日 from student;

#查詢email值為null的空行

mysql> select * from student where email is null;

#把成績都降低10%后加5分，再查詢及格成績，并按照成績從高到低排序(order by)

mysql> select studentNo as 學號, (studentResult*0.9+5) as 成績 from result where (studentResult*0.9+5)>60 order by studentResult desc;

#查詢所有年級編號為1的學員信息，按學號升序排序，從第5條記錄開始顯示4條數據(limit)

mysql> select * from student where gradeId=1 order by studentNo asc limit 4,4;

#編寫SQL語句，查看年齡比“李斯文”小的學生，要求顯示這些學生的信息

mysql> select studentName, birthday from student where birthday>(select birthday from student where studentName='李斯文');

#查詢參加最近一次Logic Java考試成績的學生的最高分和最低分

mysql> select max(studentResult) 最高分,min(studentResult) 最低分 from result where examDate=(select max(examDate) from result where subjectNo=(select subjectNo from subject where subjectName='LogicJava'));

#查詢“LogicJava”課程考試成績為60分的學生名單(采用 IN 子查詢 )

mysql> select studentNo, studentName from student where studentNo in(select studentNo from result where subjectNo=(select subjectNo from subject where subjectName='LogicJava'));

#查詢參加“LogicJava”課程最近一次考試的在讀學生名單

mysql> select studentNo, studentName from student where studentNo in( select studentNo from result where examDate=(select max(examDate) from result where subjectNo=(select subjectNo from subject where subjectName='LogicJava')));

#查詢未參加“LogicJava”課程最近一次考試的在讀學生名單(not in)

mysql> select studentNo, studentName from student where studentNo not in( select studentNo from result where examDate=(select max(examDate) from result where subjectNo=(select subjectNo from subject where subjectName='LogicJava')));

#查詢大一學期開設的課程

mysql> select subjectName from subject where gradeId=(select gradeId from grade where gradeName='大一');

#查詢未參加“HTML”課程最近一次考試的在讀學生名單

mysql> select studentNo, studentName from student where studentNo not in( select studentNo from result where examDate=(select max(examDate) from result where subjectNo=(select subjectNo from subject where subjectName='HTML')));

#高級查詢：

#查看沒有參加考試的學生

mysql> select studentName from student where studentNo in (select studentNo from result where studentResult is null);

#檢查“LogicJava”課程最近一次考試成績,如果有80分以上的成績，顯示分數排在前5名的學員學號和分數

mysql> select studentNo, studentResult from result where exists (select studentResult from result where examDate=(select max(examDate) from result where subjectNo=(select subjectNo from subject where subjectName='LogicJava')) and studentResult > 80) order by studentResult desc limit 5;

#檢查“Logic Java”課程最近一次考試成績,如果全部通過考試(60分及格)計算的該次考試平均分減5分

mysql> select avg(studentResult)-5 平均分 from result where exists(select studentResult from result where examDate=(select max(examDate) from result where subjectNo=(select subjectNo from subject where subjectName='LogicJava')) and studentResult > 60);

#如果有大一的學生，就查詢參加大一學科考試的學員學號、科目編號、考試成績，考試時間

mysql> select studentNo 學號, subjectNo 科目編號, studentResult 成績, examDate 考試時間 from result where exists (select studentNo from student where gradeId=(select gradeID from grade where gradeName='大一'));

#查詢每門課程的平均分，并且按照分數由高到低的順序排列顯示(分組查詢)

mysql> select subjectNo 課程編號,avg(studentResult) 平均分 from result group by subjectNo order by avg(studentResult) desc;

#分別統計每個年級男、女生人數

mysql> select count(*) 人數, sex 性別 from student group by sex;

#如何獲得課程平均分及格的課程編號？(分組篩選語句)

mysql> select subjectNo 課程編號,avg(studentResult) 平均分 from result group by subjectNo having avg(studentResult)>80;

#查詢出學生姓名，學生的年級，學生的課程，考試分數，考試時間字段的學生信息(多表查詢)

mysql> select studentName 姓名, gradeName 年級, subjectName 課程,studentResult 成績,examDate 考試時間 from student inner join grade on student.gradeId = grade.gradeID inner join subject on student.gradeId=subject.gradeID inner join result on student.studentNo=result.studentNo;

DCL(Data Control Language 數據庫控制語言)

#事務處理，只支持innodb和bdb類型的數據表

#關閉自動提交，同時開啟一個事務

mysql> set autocommit=0;

mysql> update acc set `money`=`money`-500 where `name`='Tom';

mysql> update acc set `money`=`money`+500 where `name`='Jerry';

#提交，將數據寫入到數據庫保存

mysql> commit;

#回到事務處理前的狀態，如果已經提交成功，則回滾無效

mysql> rollback;

#打開自動提交

mysql> set autocommit=1;

數據庫備份與恢復

#使用mysqldump備份

$ > mysqldump -u root -p myschool > /users/jason/myschool.sql;

#使用source恢復

mysql> use testdatabase;

mysql> source /user/jason/myschool.sql;

總結

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