数据库操作

一、查询

-- use myblog;

-- show tables;

insert into users (username,`password`,realname) values("chunbao","123","春宝");
-- 查询所有列
select * from users;   
-- 查询其中几列
select id,username from users;
-- 查询满足条件的所有列
select * from users where username = "jingyu" and `password` = "123";
select * from users where username = "jingyu" or `password` = "123";
-- 模糊查询
select *from users where username like "%ji%";
-- 查询排序  （不加desc为正序）
select id,realname from users where `password` like "%1%" order by id desc;

二、插入

-- 插入数据
insert into users (username,`password`,realname) values("chunbao","123","春宝");

三、修改

-- 更新
update users set realname = "鲸鱼2" where username = "jingyu";

四、删除

-- 删除
delete from users where username = "chunbao"; 

-- 软删除技术 
update users set state = "1" where username = "chunbao";
select * from users where state = "1";

软删除：即不真正删除数据，而是修改其中某一列的状态，当状态为0的时候视为已删除的数据