一、
1.创建数据库，

mysql> CREATE DATABASE IF NOT EXISTS SECOND_DB;
Query OK, 1 row affected (0.01 sec)

2.删除数据库，

mysql> DROP DATABASE IF EXISTS SECOND_DB;
Query OK, 0 rows affected (0.11 sec)

3.查询创建数据的语句，

mysql> CREATE DATABASE SECOND_DB DEFAULT CHARACTER SET UTF8MB4 COLLATE utf8mb4_bin;
Query OK, 1 row affected (0.00 sec)

mysql> SHOW CREATE DATABASE SECOND_DB;
+-----------+------------------------------------------------------------------------------------------------------------------------------+
| Database  | Create Database                                                                                                              |
+-----------+------------------------------------------------------------------------------------------------------------------------------+
| SECOND_DB | CREATE DATABASE `SECOND_DB` /*!40100 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin */ /*!80016 DEFAULT ENCRYPTION='N' */ |
+-----------+------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

4.使用数据库，查询当前默认的数据库以及使用的编码方式校验规则

mysql> USE SECOND_DB;
Database changed

mysql> SELECT @@character_set_database, @@collation_database;
+--------------------------+----------------------+
| @@character_set_database | @@collation_database |
+--------------------------+----------------------+
| utf8mb4                  | utf8mb4_bin          |
+--------------------------+----------------------+
1 row in set (0.00 sec)

二、数字，文本，日期
在一章表中定义多个字段，要使用今天提到的所有的数据类型
1.txt类型


2.number类型

注意：这些整数类型拥有额外的选项 UNSIGNED。通常，整数可以是负数或正数。如果添加 UNSIGNED属性，那么范围将从 0 开始，而不是某个负数。
3.Date类型

创建图书表：
mysql> create table book_tb(
    -> bookid int(11) comment '图书编号',
    -> book_name char(6) comment '图书名称',
    -> publishinghouse varchar(50) comment '出版社',
    -> bookreview tinytext  comment '书评',
    -> bookintroduction text  comment '图书简介',
    -> main mediumtext comment '主要内容',
    -> speak longtext comment '作者推荐',
    -> readingcheck blob comment '读者推荐',
    -> phintroduction mediumblob comment '出版社推荐',
    -> expertintroduction longblob comment '专家点评推荐',
    -> paginalnumber tinyint comment '图书页数',
    -> btnumber smallint comment '图书类数',
    -> booknumber mediumint comment '图书数量',
    -> character_num bigint comment '全书字数',
    -> publishingdate date  comment '出版日期',
    -> plansaledate datetime comment '预售日期' ,
    -> madeday timestamp comment '创作日期',
    -> borrowtime time comment '借阅时间',
    -> Booktime  year comment  '图书年份'
    -> )engine=InnoDB default character set utf8mb4 collate utf8mb4_bin;
Query OK, 0 rows affected, 1 warning (0.01 sec)
mysql>