条件
where

查看库
show databases;

选库
use test;

查看库下的表
show tables;

查表
select*from cat;

查看表结构
desc user

<增> insert
插入两列数据ued列和name列，values 后跟值
inser into user <uid,name> values <2,‘zhangsan’>

<改> update
update user set age=99 wehre name='yumli'
update  表名 set
列 1 =  新值 1,
列 2 =  新值 2
where expr

<删>delete
delete from user where uid=8;

<查>select
select * from user;(查询表名)