DB数据库，Database
DBMS数据库管理系统，DatabaMemanagmentSystem
SQL结构化查询语言，structure Query Language
开启服务
net start mysql80
登录
mysql -u root -p
显示数据库
show databases;
使用数据库
use mysql;
显示数据库表
show tables;
show tables from mysql;
显示数据库
select database();
desc stuinfo;
创建数据库
create database test;
创建数据库表
create table customer(id int,name varchar(20),password varchar(20),email varchar(30));
删除某列
alter table customer drop id;
插入一条数据
insert into stuinfo(id,name) values(1,‘John‘);
查询
select * from stuinfo;
修改
update stuinfo set name=‘jack‘ where id=1;
删除
delete from stuinfo where id=1;
显示版本
select version();
修改密码
ALTER USER ‘root‘@‘localhost‘ IDENTIFIED WITH mysql_native_password BY ‘password‘;
保存图片为二进制数据流
创建表：create table pic_bin(id INT PRIMARY KEY AUTO_INCREMENT,filename VARCHAR(100),data MEDIUMBLOB);
java存储代码
try { conn = JdbcUtil.connection(); String sql1="insert into pic_bin(filename,data) values(?,?)"; ps = conn.prepareStatement(sql1); ps.setObject(1,"a.jpg"); InputStream in=new FileInputStream("C:\\Users\\Administrator\\Desktop\\test.jpg"); ps.setObject(2,in); ps.execute(); }catch (Exception e){ e.printStackTrace(); }finally {
java读取代码
try { conn = JdbcUtil.connection(); String sql1="select filename,data from pic_bin where id=?"; ps = conn.prepareStatement(sql1); ps.setObject(1,"1"); rs=ps.executeQuery(); if(rs.next()){ String filename=rs.getString("filename"); InputStream in=rs.getBinaryStream("data"); OutputStream out=new FileOutputStream("f:\\"+filename); out.write(in.readAllBytes()); out.close(); }
原文：https://www.cnblogs.com/vocus/p/12231826.html
