# Courese-Websocket/SQL DB

https://www.facebook.com/ccckmit/videos/1853968648287309/?idorvanity=266037214366597

https://www.facebook.com/ccckmit/videos/456773166537788?idorvanity=266037214366597

# Web socket

https://deno.land/x/websocket@v0.1.4

Server

import { WebSocketClient, WebSocketServer } from "https://deno.land/x/websocket@v0.1.4/mod.ts";

const webServerSocket = new WebSocketServer(6699)
console.log(`Start at http://127.0.0.1:6699`)
webServerSocket.on("connection",function(socketClient:WebSocketClient){

    socketClient.on("message",function(message:string){
        console.log(message);
        socketClient.send(message)
    })
})

Client

import { WebSocketClient, StandardWebSocketClient } from "https://deno.land/x/websocket@v0.1.4/mod.ts";

const serverIP = "ws://127.0.0.1:6699";

const clientSocket:WebSocketClient = new StandardWebSocketClient(serverIP)

clientSocket.on("open",async function(){
    console.log("connection have been down !!!")
    clientSocket.send("meowhecker Client")

    console.log("if you want to terminate. Please enter close ")

    while (1) {
        const msg = await prompt(">")
        if(msg == "close") break
        clientSocket.send(msg)
    }
   
})

clientSocket.on("message", function (message: string) {
    console.log(message);
  });


Version 2
Server

import { WebSocketClient, WebSocketServer } from "https://deno.land/x/websocket@v0.1.4/mod.ts";


// //Record has conneted clientSocket 
//     const clientMap = new Map()
let clientSocketList:any = [];
const webServerSocket = new WebSocketServer(6699)



console.log(`Start at http://127.0.0.1:6699`)



webServerSocket.on("connection",function(socketClient:WebSocketClient){
    // clientMap.set(socketClient,null)
    clientSocketList.push(socketClient)
    socketClient.on("message",function(message:string){
        console.log(message)
        for (let i=0;i<clientSocketList.length;i++){
            console.log(`send message to ${clientSocketList[i]}`)
            clientSocketList[i].send(message)            
        }
    })
})

Client

import { WebSocketClient, StandardWebSocketClient } from "https://deno.land/x/websocket@v0.1.4/mod.ts";

const serverIP = "ws://127.0.0.1:6699";

const clientSocket:WebSocketClient = new StandardWebSocketClient(serverIP)



clientSocket.on("open",async function(){
    console.log("connection have been down !!!")
    const clientId  = await prompt("Nick Name > ")
    clientSocket.send(`${clientId} has connected`)

    console.log("if you want to terminate char room. Please enter quite ")

    //chat
    while (1) {
        const msg = await prompt(">")
        if(msg == "quite") break
        clientSocket.send(`${msg}  from (${clientId}`)

 
    }
   
})

clientSocket.on("message", function (message: MessageEvent) {
    console.log(`Receive:${message.data}`)
})

----

# White Board

JavaScript 匿名函数

if (document.load){execute coed}

(function() {})

user strice

# Database

## Normalization

- Mysql
- postgreSQL

## Denormalization

- MongoDB
- JsonDB

Sample:

let userTable =[]


userTable.push({username:"meowhecker",userpassword:"meowheckerps",phoneNumber:["12312332","23123123"]})

## Entity-relation Model


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