mysql第二次作业

作业：
   创建一个数据，db_classics
   创建一张表：t_hero
   id name nickname age address job weapon group
   1 张百川玉皇大帝 200000
   2 孙悟空齐天大圣
   3 林妹妹
创建数据库，创建英雄表
添加对应的约束条件
插入80条数据
通过alter添加两个新的字段
通过alter删除一个字段
重命名一张表

create database if not exists db_classics default charset=utf8mb4;
# 如果数据库存在，也不报错，特别适合于写脚本时，编码使用utf8mb4

   create table if not exists t_hero(
       id int primary key auto_increment,
       name varchar(50) not null unique,
       nickname varchar(50) not null unique,
       age int check(age >= 18) default 20,
       address varchar(50) not null unique,
       gender varchar(10) default "男",
       job varchar(10),
       weapon varchar(50),
       grou int not null default 1,
   )；

insert into t_hero values(1,"张百川","玉皇大帝",200000,"天庭","男","刺客","不知道",1)
insert into t_hero values(2,"孙悟空","齐天大圣",600,"花果山","男","战士","金箍棒",2)
insert into t_hero values(3,"林黛玉","林妹妹",18,"贾府","女","法师","面巾",3)

修改表结构：
   增加新的列
   ALTER TABLE t_hero ADD "爱好" varchar not null；
   ALTER TABLE t_hero ADD "评价" default '强';

删除列
ALTER TABLE t_hero DROP "爱好"

表重命名
ALTER TABLE t_hero RENAME t_hero1;

总

create database if not exists db_classics default charset=utf8mb4;
# 如果数据库存在，也不报错，特别适合于写脚本时，编码使用utf8mb4
   create table if not exists t_hero(
       id int primary key auto_increment,
       name varchar(50) not null unique,
       nickname varchar(50) not null unique,
       age int check(age >= 18),
       address varchar(50) not null unique,
       gender varchar(10) not null default "男",
       job varchar(10),
       weapon varchar(50),
       grou int not null default 1
   );

insert into t_hero values(1,"张百川","玉皇大帝",200000,"天庭","男","刺客","不知道",1);
insert into t_hero values(2,"孙悟空","齐天大圣",600,"花果山","男","战士","金箍棒",2)
insert into t_hero values(3,"林黛玉","林妹妹",18,"贾府","女","法师","面巾",3)

#修改表结构：
#增加新的列
   ALTER TABLE t_hero ADD 爱好 varchar(100) not null;
   ALTER TABLE t_hero ADD 评价 varchar(100) default "强";
#删除列
   ALTER TABLE t_hero DROP 爱好;
#表重命名
   ALTER TABLE t_hero RENAME t_hero1;