-- 创建数据库
create database python_test_1 charset=utf8;
-- 使用数据库
use python_test_1;
-- students表
create table students(
  id int unsigned primary key auto_increment not null,
  name varchar(20) default '',
  age tinyint unsigned default 0,
  height decimal(5,2),
  gender enum('男','女','中性','保密') default '保密',
  cls_id int unsigned default 0,
  is_delete bit default 0
);
-- classes表
create table classes (
  id int unsigned auto_increment primary key not null,
  name varchar(30) not null
);

-- 向students表中插入数据
insert into students values
(0,'小明',18,180.00,2,1,0),
(0,'小月月',18,180.00,2,2,1),
(0,'彭于晏',29,185.00,1,1,0),
(0,'刘德华',59,175.00,1,2,1),
(0,'黄蓉',38,160.00,2,1,0),
(0,'凤姐',28,150.00,4,2,1),
(0,'王祖贤',18,172.00,2,1,1),
(0,'周杰伦',36,NULL,1,1,0),
(0,'程坤',27,181.00,1,2,0),
(0,'刘亦菲',25,166.00,2,2,0),
(0,'金星',33,162.00,3,3,1),
(0,'静香',12,180.00,2,4,0),
(0,'郭靖',12,170.00,1,4,0),
(0,'周杰',34,176.00,2,5,0);

-- 向classes表中插入数据
insert into classes values (0, "python_01期"), (0, "python_02期");

select * from 表名;

select * from students;

select 列1,列2,... from 表名;

select name from students;

select id as 序号, name as 名字, gender as 性别 from students;

-- 如果是单表查询 可以省略表明
select id, name, gender from students;
-- 表名.字段名
select students.id,students.name,students.gender from students;
-- 可以通过 as 给表起别名 
select s.id,s.name,s.gender from students as s;

select distinct 列1,... from 表名;

select distinct gender from students;