show database;
create database school_of_three_kindoms charset=utf8;
select database();
drop database school_of_three_kindoms;
show tables;
desc students;
- -- 创建学生基本信息表
create table students(
-- 学籍号:int unsigned无符号整型, auto_increment自增,primary key设置为主键,not null非空
id int unsigned auto_increment primary key not null,
-- 姓名: varchar(30)可变字符类型, default ""默认为空字符
name varchar(30) default "",
-- 年龄: tinyint unsigned无符号整型, default 0 默认为 0
age tinyint unsigned default 0,
-- 身高: 浮点型(5个数字,包含2个小数,如 180.05)
height decimal(5, 2),
-- 性别: enum枚举类型("1"对应"男","2"对应"女","3"对应"保密"")
gender enum("男","女","保密"),
);
alter table students add is_delete bit default 0;
alter table students change name new_name varchar(30) default "";
alter table students modify name varchar(30) default "";
alter table students drop age;
alter table students drop age;
alter table students rename to super_students;
show create table students;
- insert into students values
(null, "曹操", 50, 183.05, 1),
(null, "夏侯惇", 40, 193.05, 1),
(null, "许褚", 42, 186.05, 1);
update students set age = 51 where id = 5;
select * from students;
select id, name from students;
delete from students where id = 4;
sql语句入门导图