目录：
　　1.新建数据库
　　2.新建数据表
　　3.查看表结构
　　4.增删改查
　　建立一个数据库students
　　建立一块数据表class1
　　内容包括：
　　id 主键 自动编号 无符号位 SMALLINT类型
　　name VARCHAR(30)类型 非空 值
　　school VARCHAR(30) 非空 默认值chengdu college
　　代码如下：
　　1.建立数据库
　　mysql> CREATE DATABASE students;
　　Query OK， 1 row affected (0.07 sec)
　　2.进入数据库
　　mysql> USE students;
　　Database changed
　　3.新建表
mysql> CREATE TABLE class1 (
-> id SMALLINT UNSIGNED AUTO_INCREMENT ，
-> name VARCHAR(30) NOT NULL UNIQUE KEY ，
-> school VARCHAR(30) DEFAULT 'chengdu_collage' ，
-> PRIMARY KEY(id)
-> );
Query OK， 0 rows affected (0.09 sec)
　　4.查看表结构
mysql> DESC class1;
+--------+----------------------+------+-----+-----------------+----------------+
| Field  | Type                 | Null | Key | Default         | Extra          |
+--------+----------------------+------+-----+-----------------+----------------+
| id     | smallint(5) unsigned | NO   | PRI | NULL            | auto_increment |
| name   | varchar(30)          | NO   | UNI | NULL            |                |
| school | varchar(30)          | YES  |     | chengdu_collage |                |
+--------+----------------------+------+-----+-----------------+----------------+
3 rows in set (0.00 sec)
　　1.插入(INSERT)
1.INSERT INTO tb_name [(col_name...)] {VALUES|VALUE}({expr | DEFAULT}，....)，(...)...
例子：
mysql> INSERT INTO class1 (name) VALUES ('john');
Query OK， 1 row affected (0.01 sec)
mysql> INSERT INTO class1 VALUES (DEFAULT，'jobs'，'chengdu_agricultural_college');
Query OK， 1 row affected (0.01 sec)
2.INSERT INTO tb_name SET col_name = {expr | DEFAULT}，...
例子：
mysql> INSERT INTO class1 SET name='tom';
Query OK， 1 row affected (0.02 sec)
mysql> INSERT INTO class1 SET name='lues'，school='chengdu_agricultural_college';
Query OK， 1 row affected (0.01 sec)
　　2.修改(UPDATE)
1.UPDATE [LOW_PRIORITY] [IGNORE] table_reference
SET col_name1={expr1|DEFAULT} [， col_name2={expr2|DEFAULT}] ...
例子：
mysql> UPDATE class1
-> SET name='lues2' WHERE name='lues';
Query OK， 1 row affected (0.07 sec)
Rows matched: 1  Changed: 1  Warnings: 0
　　3.删除(DELETE)
1.DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name
[WHERE where_condition]
例子：
mysql> DELETE FROM class1 WHERE name='lues2';
Query OK， 1 row affected (0.01 sec)
　　4.查询(SELECT)
1.简单查询
mysql> SELECT * FROM class1;
+----+------+------------------------------+
| id | name | school                       |
+----+------+------------------------------+
|  1 | john | chengdu_collage              |
|  2 | jobs | chengdu_agricultural_college |
|  3 | tom  | chengdu_collage              |
+----+------+------------------------------+
3 rows in set (0.00 sec)
2.简单的条件查询
mysql> SELECT * FROM class1 WHERE id > 1;
+----+------+------------------------------+
| id | name | school                       |
+----+------+------------------------------+
|  2 | jobs | chengdu_agricultural_college |
|  3 | tom  | chengdu_collage              |
+----+------+------------------------------+
2 rows in set (0.00 sec)
3.简单的分组查询
mysql> SELECT * FROM class1 GROUP BY school DESC;
+----+------+------------------------------+
| id | name | school                       |
+----+------+------------------------------+
|  1 | john | chengdu_collage              |
|  2 | jobs | chengdu_agricultural_college |
+----+------+------------------------------+
2 rows in set (0.00 sec)
4.简单的排序查询
mysql> SELECT * FROM class1 ORDER BY id DESC;
+----+------+------------------------------+
| id | name | school                       |
+----+------+------------------------------+
|  3 | tom  | chengdu_collage              |
|  2 | jobs | chengdu_agricultural_college |
|  1 | john | chengdu_collage              |
+----+------+------------------------------+
3 rows in set (0.00 sec)