MySQL: MySQL数据学习专题

专题图： 编号：ylbtech MySQL100010010，揭示Google，百度，facebook，互动百科为什么选择MySQL做数据库

内容简介  MySQL目录

 

--===================================
--ylb：MySQL
--1，MySQL提纲
--16:41 2012-1-6
--我的人生除了技术，我还能拥有什么？
--那我就把此生献给她吧！希望她给能给更多的人带来心灵的温暖
--===================================
 
1,什么是MySQL？
 
2，数据类型

3，基本操作命令

4，数据库的操作

5，建表、约束、

6，表结构的修改与约束（添加、删除）

7，数据库的备份

8，日常维护与管理

9，高级查询（子查询，函数运用）

 

技术与环境

操作系统:	windows	语言类别:	SQL
thankyou:	sunshine, 谢谢你的默默付出	数据库:	MySQL
学习软件:	mysql-essential-5.1.55-win32
课程总策划:	yuanbo	English name:	sunshine
个人主页:	http://www.cnblogs.com/ylbtech/
科研团队:	ylbtech	教研团队:	ylbtech

 

MySQL: 1,什么是MySQL？

--============================================
--ylb: MySQL
--1,什么是MySQL？
--============================================
 
    MySQL是一个真正的多用户、多线程SQL数据库服务器。SQL（结构化查询语言）是世界上最流行的和标准化的数据库语言。MySQL是以一个客户机/服务器结构的实现，它由一个服务器守护程序mysqld和很多不同的客户程序和库组成。
SQL是一种标准化的语言，它使得存储、更新和存取信息更容易。例如，你能用SQL语言为一个网站检索产品信息及存储顾客信息，同时MySQL也足够快和灵活以允许你存储记录文件和图像。
MySQL 主要目标是快速、健壮和易用。最初是因为我们需要这样一个SQL服务器，它能处理与任何可不昂贵硬件平台上提供数据库的厂家在一个数量级上的大型数据库，但速度更快，MySQL就开发出来。自1996年以来，我们一直都在使用MySQL，其环境有超过 40 个数据库，包含 10,000个表，其中500多个表超过7百万行，这大约有100 个吉字节(GB)的关键应用数据。
MySQL建立的基础是业已用在高要求的生产环境多年的一套实用例程。尽管MySQL仍在开发中，但它已经提供一个丰富和极其有用的功能集。
MySQL的官方发音是“My Ess Que Ell”(不是 MY-SEQUEL )。

 

MySQL：2，数据类型

 --================================
--ylb:MySQL
--1,数据类型
--17:04 2012-1-6
--================================

MySQL：3，基本操作命令 

 --================================
--ylb:MySQL
--1,数据类型
--17:04 2012-1-6
--================================
 
 　 1、显示数据库列表。
　　show databases;
　　刚开始时才两个数据库：mysql和test。mysql库很重要它里面有MYSQL的系统信息，我们改密码和新增用户，实际上就是用这个库进行操作。
　　2、显示库中的数据表：
　　use mysql； //打开库，学过FOXBASE的一定不会陌生吧
　　show tables;
　　3、显示数据表的结构：
　　describe 表名;
　　4、建库：
　　create database 库名;
　　5、建表：
　　use 库名；
　　create table 表名 (字段设定列表)；
　　6、删库和删表:
　　drop database 库名;
　　drop table 表名；
　　7、将表中记录清空：
　　delete from 表名;
　　8、显示表中的记录：
　　select * from 表名; 
      9、显示use的数据库名：
      SELECT DATABASE();
      10、显示当前的user：
      SELECT USER();

MySQL：4，数据库的操作

--================================
--ylb:MySQL
--1，数据库的操作
--2，建库、删库、建表、操作（增删改查）、删表
--17:04 2012-1-6
--================================
 
Enter password: ****
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.0.45-community-nt-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> --1,
mysql> drop database if exists yb;
Query OK, 5 rows affected (0.19 sec)
mysql> --2,
mysql> create database yb;
Query OK, 1 row affected (0.00 sec)
mysql> --3,
mysql> use yb;
Database changed
mysql> --4,create table
mysql> create table users
    -> (
    -> userID int not null,
    -> username varchar(100)
    -> );
Query OK, 0 rows affected (0.11 sec)
mysql> --5,desc
mysql> desc users;
+----------+--------------+------+-----+---------+-------+
| Field    | Type         | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| userID   | int(11)      | NO   |     |         |       |
| username | varchar(100) | YES  |     | NULL    |       |
+----------+--------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> --6,insert
mysql> insert into users(userID,username) values(101,'pengYun');
Query OK, 1 row affected (0.00 sec)
mysql> insert into users(userID,username) values(102,'wenFei');
Query OK, 1 row affected (0.00 sec)
mysql> --7,select
mysql> select * from users;
+--------+----------+
| userID | username |
+--------+----------+
|    101 | pengYun  |
|    102 | wenFei   |
+--------+----------+
2 rows in set (0.00 sec)
mysql> --8,update
mysql> update users set username='huWenFei' where userID=102;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0
mysql> select * from users;
+--------+----------+
| userID | username |
+--------+----------+
|    101 | pengYun  |
|    102 | huWenFei |
+--------+----------+
2 rows in set (0.00 sec)
mysql> --9,delete
mysql> delete from users where userid=101;
Query OK, 1 row affected (0.00 sec)
mysql> select * from users;
+--------+----------+
| userID | username |
+--------+----------+
|    102 | huWenFei |
+--------+----------+
1 row in set (0.00 sec)
mysql> --10,truncate table
mysql> truncate table users;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from users;
Empty set (0.00 sec)
mysql> --11,commit
mysql> commit;
Query OK, 0 rows affected (0.00 sec)
mysql> --12,drop table
mysql> drop table users;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from users;
ERROR 1146 (42S02): Table 'yb.users' doesn't exist
mysql> --13,
mysql> drop database yb;
Query OK, 0 rows affected (0.00 sec)
mysql> use yb;
ERROR 1049 (42000): Unknown database 'yb'
mysql> --14,
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| phpmyadmin         |
| test               |
| ylb                |
+--------------------+
5 rows in set (0.06 sec)
mysql>

MySQL：4_2,表的基本约束

--================================
--ylb:MySQL
--1,表的约束添加
--2，主键、外键、唯一、检查、非空、默认
--17:04 2012-1-6
--================================
 
--====================================
--P1:默认约束
--====================================
Enter password: ****
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.0.45-community-nt-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> --1,
mysql> drop database if exists yb;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> --2,
mysql> create database yb;
Query OK, 1 row affected (0.00 sec)
mysql> --3,
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| phpmyadmin         |
| test               |
| yb                 |
| ylb                |
+--------------------+
6 rows in set (0.00 sec)
mysql> --4,
mysql> use yb;
Database changed
mysql> --5,create table
mysql>  create table users
    ->  (
    ->  userID int not null primary key,
    ->  username varchar(100) not null,
    ->  nicheng varchar(100) not null unique,
    ->  sex char(2) check(sex in('男','女')),
    ->  regdate date
    ->  );
Query OK, 0 rows affected (0.06 sec)
mysql> desc users;
+----------+--------------+------+-----+---------+-------+
| Field    | Type         | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| userID   | int(11)      | NO   | PRI |         |       |
| username | varchar(100) | NO   |     |         |       |
| nicheng  | varchar(100) | NO   | UNI |         |       |
| sex      | char(2)      | YES  |     | NULL    |       |
| regdate  | date         | YES  |     | NULL    |       |
+----------+--------------+------+-----+---------+-------+
5 rows in set (0.00 sec)
mysql> --6,
mysql> create table orders
    -> (
    -> orderid int not null primary key,
    -> total number(6,2) check(total>0),
    -> userid int not null references users(userid)
    -> );
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use near 'numbe
r(6,2) check(total>0),
userid int not null references users(userid)
)' at line 4
mysql>
mysql>  create table orders
    ->  (
    ->  orderid int not null primary key,
    ->  total numeric(6,2) check(total>0),
    ->  userid int not null references users(userid)
    ->  );
Query OK, 0 rows affected (0.08 sec)
mysql> desc orders;
+---------+--------------+------+-----+---------+-------+
| Field   | Type         | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+-------+
| orderid | int(11)      | NO   | PRI |         |       |
| total   | decimal(6,2) | YES  |     | NULL    |       |
| userid  | int(11)      | NO   |     |         |       |
+---------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
mysql> --7,
mysql> show tables;
+--------------+
| Tables_in_yb |
+--------------+
| orders       |
| users        |
+--------------+
2 rows in set (0.00 sec)
mysql> --8,auto_increment
mysql> create table autoUsers
    -> (
    -> userid int auto_increment primary key,
    -> username varchar(100)
    -> );
Query OK, 0 rows affected (0.09 sec)
mysql> desc autoUsers;
+----------+--------------+------+-----+---------+----------------+
| Field    | Type         | Null | Key | Default | Extra          |
+----------+--------------+------+-----+---------+----------------+
| userid   | int(11)      | NO   | PRI | NULL    | auto_increment |
| username | varchar(100) | YES  |     | NULL    |                |
+----------+--------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
mysql> insert into autoUsers(username) values('pengYun');
Query OK, 1 row affected (0.00 sec)
mysql> insert into autoUsers(username) values('weiFei');
Query OK, 1 row affected (0.00 sec)
mysql> select * from autoUsers;
+--------+----------+
| userid | username |
+--------+----------+
|      1 | pengYun  |
|      2 | weiFei   |
+--------+----------+
2 rows in set (0.00 sec)
mysql>

MySQL：4_3,后加约束与修改列

--================================
--ylb:MySQL
--1,后加约束与修改列
--2，主键、外键、唯一、检查、非空、默认
--17:04 2012-1-6
--================================
 
--============================================
-- P1:删除约束
--============================================
Enter password: ****
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.0.45-community-nt-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> --1,
mysql> drop database if exists yb;
Query OK, 1 row affected (0.00 sec)
mysql> --2,
mysql> create database yb;
Query OK, 1 row affected (0.00 sec)
mysql> --3,
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| phpmyadmin         |
| test               |
| yb                 |
| ylb                |
+--------------------+
6 rows in set (0.00 sec)
mysql> --4,
mysql> use yb;
Database changed
mysql> --5,
mysql> create table users
    -> (
    -> userID int not null,
    -> username varchar(100),
    -> nicheng varchar(100) not null,
    -> sex char(2),
    -> regdate date
    -> );
Query OK, 0 rows affected (0.11 sec)
mysql> --5,
mysql> desc users;
+----------+--------------+------+-----+---------+-------+
| Field    | Type         | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| userID   | int(11)      | NO   |     |         |       |
| username | varchar(100) | YES  |     | NULL    |       |
| nicheng  | varchar(100) | NO   |     |         |       |
| sex      | char(2)      | YES  |     | NULL    |       |
| regdate  | date         | YES  |     | NULL    |       |
+----------+--------------+------+-----+---------+-------+
5 rows in set (0.00 sec)
mysql> --7,add pk
mysql> alter table users
    -> add constraint pk_users_userid primary key(userid);
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> --8,add unique
mysql> alter table users
    -> add constraint un_users_nicheng unique(nicheng);
Query OK, 0 rows affected (0.03 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> --9,add check
mysql> alter table users
    -> add constraint ch_users_sex check(sex in('男','女'));
Query OK, 0 rows affected (0.11 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> --10,modify not null|null
mysql> alter table users
    -> modify username varchar(100) not null;
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> --11,modify default
mysql> alter table users
    -> modify regdate date default '2012-1-1';
Query OK, 0 rows affected (0.16 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> --12,
mysql> desc users;
+----------+--------------+------+-----+------------+-------+
| Field    | Type         | Null | Key | Default    | Extra |
+----------+--------------+------+-----+------------+-------+
| userID   | int(11)      | NO   | PRI |            |       |
| username | varchar(100) | NO   |     |            |       |
| nicheng  | varchar(100) | NO   | UNI |            |       |
| sex      | char(2)      | YES  |     | NULL       |       |
| regdate  | date         | YES  |     | 2012-01-01 |       |
+----------+--------------+------+-----+------------+-------+
5 rows in set (0.00 sec)
mysql> --13,
mysql> create table orders
    -> (
    -> orderID int auto_increment primary key,
    -> total numeric(6,2) check(total>0),
    -> userid int not null
    -> );
Query OK, 0 rows affected (0.09 sec)
mysql> --14,add fk
mysql> alter table orders
    -> add constraint fk_orders_users_userid foreign key(userid) references
    -> users(userid);
Query OK, 0 rows affected (0.09 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> desc orders;
+---------+--------------+------+-----+---------+----------------+
| Field   | Type         | Null | Key | Default | Extra          |
+---------+--------------+------+-----+---------+----------------+
| orderID | int(11)      | NO   | PRI | NULL    | auto_increment |
| total   | decimal(6,2) | YES  |     | NULL    |                |
| userid  | int(11)      | NO   | MUL |         |                |
+---------+--------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)
mysql> --15,drop constraint
mysql> alter table users
    -> drop constraint ch_users_sex;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use near 'const
raint ch_users_sex' at line 2
mysql> --16,修改表结构
mysql> create table emp
    -> (
    -> empno int,
    -> ename varchar(100)
    -> );
Query OK, 0 rows affected (0.09 sec)
mysql> desc emp;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| empno | int(11)      | YES  |     | NULL    |       |
| ename | varchar(100) | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
2 rows in set (0.05 sec)
mysql> --17,add column
mysql> alter table emp
    -> add sex char(2);
Query OK, 0 rows affected (0.09 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> desc emp;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| empno | int(11)      | YES  |     | NULL    |       |
| ename | varchar(100) | YES  |     | NULL    |       |
| sex   | char(2)      | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.01 sec)
mysql> alter table emo
    -> ;
ERROR 1146 (42S02): Table 'yb.emo' doesn't exist
mysql> alter table emp
    -> add nicheng varchar(100) not null unique;
Query OK, 0 rows affected (0.08 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> desc emp;
+---------+--------------+------+-----+---------+-------+
| Field   | Type         | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+-------+
| empno   | int(11)      | YES  |     | NULL    |       |
| ename   | varchar(100) | YES  |     | NULL    |       |
| sex     | char(2)      | YES  |     | NULL    |       |
| nicheng | varchar(100) | NO   | PRI |         |       |
+---------+--------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
mysql> --18,drop column
mysql> alter table emp
    -> drop column nicheng;
Query OK, 0 rows affected (0.13 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> desc emp;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| empno | int(11)      | YES  |     | NULL    |       |
| ename | varchar(100) | YES  |     | NULL    |       |
| sex   | char(2)      | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
mysql>

MySQL：4_4,视图(View)

--================================
--ylb:MySQL
--1,视图（View）创建于管理
--17:04 2012-1-6
--================================
Enter password: ****
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.0.45-community-nt-log MySQL Community Edition (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> --1,
mysql> drop database if exists yb;
Query OK, 3 rows affected (0.06 sec)
mysql> --2,
mysql> create database yb;
Query OK, 1 row affected (0.00 sec)
mysql> --3,
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| phpmyadmin         |
| test               |
| yb                 |
| ylb                |
+--------------------+
6 rows in set (0.00 sec)
mysql> --4,
mysql> use yb;
Database changed
mysql> --5,create table
mysql> create table users
    -> (
    -> userID int auto_increment primary key,
    -> username varchar(100)
    -> );
Query OK, 0 rows affected (0.11 sec)
mysql> insert into users(username) values('weiFei');
Query OK, 1 row affected (0.00 sec)
mysql> insert into users(username) values('xiaoLiu');
Query OK, 1 row affected (0.00 sec)
mysql> select * from users;
+--------+----------+
| userID | username |
+--------+----------+
|      1 | weiFei   |
|      2 | xiaoLiu  |
+--------+----------+
2 rows in set (0.00 sec)
mysql> --6,create view
mysql> create view v_users
    -> as
    -> select * from users;
Query OK, 0 rows affected (0.05 sec)
mysql> --7,
mysql> show tables;
+--------------+
| Tables_in_yb |
+--------------+
| users        |
| v_users      |
+--------------+
2 rows in set (0.01 sec)
mysql> --8,desc view
mysql> desc v_users;
+----------+--------------+------+-----+---------+-------+
| Field    | Type         | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+-------+
| userID   | int(11)      | NO   |     | 0       |       |
| username | varchar(100) | YES  |     | NULL    |       |
+----------+--------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> desc users;
+----------+--------------+------+-----+---------+----------------+
| Field    | Type         | Null | Key | Default | Extra          |
+----------+--------------+------+-----+---------+----------------+
| userID   | int(11)      | NO   | PRI | NULL    | auto_increment |
| username | varchar(100) | YES  |     | NULL    |                |
+----------+--------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)
mysql> --9,select view
mysql> select * from v_users;
+--------+----------+
| userID | username |
+--------+----------+
|      1 | weiFei   |
|      2 | xiaoLiu  |
+--------+----------+
2 rows in set (0.00 sec)
mysql> --10,drop view
mysql> drop view v_users;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from v_users;
ERROR 1146 (42S02): Table 'yb.v_users' doesn't exist
mysql>

MySQL: 4_5,修改表约束

--===========================================
--ylb:MySQL
--1，修改表约束
--9:18 2012-1-7
--===========================================
 
用alter table语句：

完整用法：
ALTER [IGNORE] TABLE tbl_name
    alter_specification [, alter_specification] ...

alter_specification:
    table_option ...
  | ADD [COLUMN] column_definition [FIRST | AFTER col_name ]
  | ADD [COLUMN] (column_definition,...)
  | ADD {INDEX|KEY} [index_name] [index_type] (index_col_name,...)
  | ADD [CONSTRAINT [symbol]]
        PRIMARY KEY [index_type] (index_col_name,...)
  | ADD [CONSTRAINT [symbol]]
        UNIQUE [INDEX|KEY] [index_name] [index_type] (index_col_name,...)
  | ADD [FULLTEXT|SPATIAL] [INDEX|KEY] [index_name] (index_col_name,...)
  | ADD [CONSTRAINT [symbol]]
        FOREIGN KEY [index_name] (index_col_name,...)
        [reference_definition]
  | ALTER [COLUMN] col_name {SET DEFAULT literal | DROP DEFAULT}
  | CHANGE [COLUMN] old_col_name column_definition
        [FIRST|AFTER col_name]
  | MODIFY [COLUMN] column_definition [FIRST | AFTER col_name]
  | DROP [COLUMN] col_name
  | DROP PRIMARY KEY
  | DROP {INDEX|KEY} index_name
  | DROP FOREIGN KEY fk_symbol
  | DISABLE KEYS
  | ENABLE KEYS
  | RENAME [TO] new_tbl_name
  | ORDER BY col_name [, col_name] ...
  | CONVERT TO CHARACTER SET charset_name [COLLATE collation_name]
  | [DEFAULT] CHARACTER SET charset_name [COLLATE collation_name]
  | DISCARD TABLESPACE
  | IMPORT TABLESPACE

index_col_name:
    col_name [(length)] [ASC | DESC]

index_type:
    USING {BTREE | HASH}


删除 主键 和外键约束:

ALTER TABLE mytablename
  DROP PRIMARY KEY
  DROP FOREIGN KEY fk_symbol;


还有就是怎么样查询 约束; 

你可以通过查看该表的 创建语句来 查看 约束：

SHOW CREATE TABLE mytablename;

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