1.增
use myblog;
show tables;
insert into users(username, `password`, realname) values ('zhangsan', '123', '张三');
2.查
use myblogs;
show tables;
select * from users; --查询所有
select id,username form users; --查询id和username
select * from users where username='zhangsan'; --条件查询
select * from users where username='zhangsan' and `password`='123'; --并且
select * from users where username='zhangsan' or `password`='123'; --或者
select * from users where username like '%zhang%'; --模糊查询
select * from users where password like '%1%' order by id desc; --desc表示倒序，不加默认正序
select * form users where state <> '0'; -- <>表示不等于0
select count(id) as `count` from blogs; -- 查询总数
select * from blogs order by id desc limit 2; -- 查询第一页的两条数据
select * from blogs order by id desc limit 2 offset 2; -- 查询第二页的两条数据
3.改（更新）
如果遇到update users set realname...报错的话，先执行 SET SQL_SAFE_UPDATES = 0; 然后删掉再执行更新操作
update users set realname='李四2' where username='lisi';
4.删
delete from users where username='lisi';
-- 日常开发中我们通常是采用软删除
update users set state='0' where username='lisi';
5. 多表联查
select blogs.*, users.username, users.nickname
from blogs inner join users on users.id = blogs.userid
where users.username = 'lisi'
