server side documentation

README.md

@@ -377,4 +377,6 @@ MySQL localhost:3306 ssl SQL> select * from store_test;
 // change to MySQL binary folder
 C:\> "C:\Program Files\MySQL\MySQL Server 8.0\bin\mysqldump.exe" -u root -p nusbank > d:/nusbank.sql
 
-```
+```
+
+[Next](./server-side.md)

server-side.md

@@ -0,0 +1,310 @@
+# Server Side
+
+## Tools
+* VSCode
+* Node JS
+* [Postman](https://www.postman.com/downloads/)
+  + For Ubuntu 20.04 installation
+    ```
+    $ sudo snap install postman
+    ```
+* Packages
+  + mysql : MySql database CRUD
+  + express : REST framework
+  + body-parser : for parsing html body json content
+
+## Prepare Project
+* Create a new project folder
+
+```bash
+// init new Node project. create package.json file
+$ npm init
+
+// install packages
+$ npm install --save mysql
+$ npm install --save express body-parser
+```
+
+### Quick Fix for MySQL8
+* node js packages still do not support new password scheme of MySQL8.
+* thus switch to old native scheme for node JS support. (Note :  The native scheme is less secure)
+* Update MySql root password to native
+
+```sql
+mysql> ALTER USER 'root'@'localhost' 
+IDENTIFIED WITH mysql_native_password 
+BY 'password';
+```
+
+## Accessing database from nodejs
+
+* CRUD operation - CREATE, READ, UPDATE, DELETE (For database operation)
+* database.js
+```javascript
+const mysql = require("mysql");
+
+parameters = {
+    host: "localhost",
+    user: "root",
+    password: "7572137",
+    database: "nusbank",
+    multipleStatements: true,
+};
+
+let connection = mysql.createConnection(parameters);
+connection.connect((error) => {
+    if (error){
+        console.log(error);
+    } else {
+        console.log("Connection was successfull");
+    }
+});
+
+connection.query(`SELECT * FROM users LIMIT 5`, (err, result) => {
+    if (err){
+        console.log(err);
+    }else{
+        console.log(result);
+    }
+});
+
+let newuser = { id: 599,
+        name: "Harry Lim",
+    mail: "harrylim@abc.com",
+    mobile: "99887788",
+    nric: "S223311A"
+};
+
+connection.query(`DELETE FROM users WHERE user_id = ${newuser.id}`, (err, result) =>{
+    if (err){
+        console.log(err);
+    }else{
+        console.log(result);
+    }
+});
+
+connection.query(
+    `INSERT INTO users(user_id, name, mail, mobile, nric) 
+    VALUES (${newuser.id},'${newuser.name}', '${newuser.mail}', ${newuser.mobile}, '${newuser.nric}')`,
+    (err, results) => {
+        if (err){
+            console.log(err);
+        } else {
+            if (results["affectedRows"] != 0) {
+                console.log("Added", results);
+            }
+        }        
+    });
+
+//
+connection.query(`DELETE FROM users WHERE user_id = ${newuser.id}`, (err, result) =>{
+    if (err){
+        console.log(err);
+    }else{
+        console.log(result);
+    }
+});
+
+// query highest monthly transaction
+connection.query(`SELECT a.user_id, u.name, a.acct_number, t.date, COUNT(a.user_id) as cmonth
+FROM transactions AS t
+INNER JOIN accounts AS a
+ON a.acct_number = t.acct_number
+INNER JOIN users AS u
+ON u.user_id = a.user_id
+GROUP BY a.user_id, MONTH(t.date), YEAR(t.date)
+ORDER BY cmonth DESC
+LIMIT 1`,
+(err, results) => {
+    if (err){
+        console.log(err);
+    } else {
+        if (results["affectedRows"] != 0) {
+            console.log("Highest Montly", results);
+        }
+    }        
+});
+```
+
+## API
+* Application Programming Interface
+* Purpose : contract defining how different systems will communicate
+* Styles
+  + REST
+  + RPC : SOAP (xml format)
+  + GraphQL : By Facebook. For databases
+  + Event-Driven : For streaming services. Require realtime update.
+* REST API to expose data from MySQL
+
+### REST
+* http
+* POST, GET, PUT, DELETE
+* Components
+  + URI
+  + headers
+  + key
+  + method
+
+Component | Description
+----|-----
+API name | 
+Description |
+Method | GET, POST, PUT, DELETE
+URI | Location, port (example:/user/id)
+Headers, Parameters, Body |
+Authentication & Authorisation | Key, bearer token
+Response | Status Code, body
+
+* ExpressJS : Framework for implementing REST server
+* apis.js 
+```javascript
+const express = require('express');
+const bodyParser = require('body-parser');
+
+var app = express();
+
+// parse body formatted in JSON
+app.use(bodyParser.json());
+
+app.get('/', (req, res) => {
+    res.send('Hello Express');
+});
+
+app.get('/squared', (req, res) => {
+    // JSON format
+    // { "number": 2}
+    number = req.body.number;
+    squared = number * number;
+
+    res.send(`Squared : ${squared}`);
+
+    // from POSTMAN.. set Body raw content as JSON data
+    // { "number": 3 }
+});
+
+app.listen(process.env.PORT || 3000);
+
+```
+* Powershell Environment Variable
+
+```Powershell
+// create variable PORT=3001
+PS> $Env:PORT = 3001
+
+// return PORT value
+PS> $Env:PORT
+
+````
+
+
+## API & database integration
+
+* server.js
+
+```javascript
+const mysql = require("mysql");
+const express = require("express");
+const bodyParser = require("body-parser");
+
+parameters = {
+    host: "localhost",
+    user: "root",
+    password: "7572137",
+    database: "nusbank",
+    multipleStatements: true,
+};
+
+let connection = mysql.createConnection(parameters);
+connection.connect((error) => {
+    if (error){
+        console.log(error);
+    } else {
+        console.log("Connection was successfull");
+    }
+});
+
+/// Connected
+let app = express();
+
+app.use(bodyParser.json());
+
+// GET route for /user query
+app.get("/user", (request, response) => {
+    connection.query("SELECT * FROM users LIMIT 10", (err, result) => {
+        if (err) {
+            response.send("Some error occur");
+        }
+        else {
+            response.send(result);
+        }    
+    });
+});
+
+// GET route for /user/id query
+// with body = { "id": 2 }
+app.get("/user/id", (request, response) => {
+    console.log(request.body);
+    //
+    connection.query(`SELECT * FROM users WHERE user_id = ${request.body.id}`, 
+    (err, result) => {
+        if (err) {
+            response.send("Some id error occur");
+        }
+        else {
+            response.send(result);
+        }    
+    });
+});
+
+/* 
+ POST route for /user add
+  with body = {
+    "id":598,
+    "name": "John Heng",
+    "mail": "johnheng@xyz.com",
+    "mobile": 91191100,
+    "nric" : "S1234765F"
+}
+*/
+app.post("/user", (request, response) => {
+    console.log(request.body);
+    //
+    connection.query(`INSERT INTO users(user_id, name, mail, mobile, nric) 
+    VALUES (${request.body.id},'${request.body.name}', '${request.body.mail}', ${request.body.mobile}, '${request.body.nric}')`, 
+    (err, result) => {
+        if (err) {
+            response.send("Some record error occur");
+        }
+        else {
+            response.send("Record saved successfully");
+        }    
+    });
+});
+
+// listen port 3000
+app.listen(3000);
+
+```
+
+## REST and CRUD co-relation
+
+REST | CRUD | Description
+----|-----|----
+GET | READ | Read record from database table
+POST | CREATE | Create record into database table
+PUT | UPDATE | Update record into database table
+DELETE | DELETE | Delete record from database table
+
+## Homework 2
+* API express js code and validate using Postman
+* API documentation
+
+Component | Description
+----|-----
+API name | getUserId
+Description | Get User by ID
+Method | GET
+URI | /user/id
+Headers, Parameters, Body | body { "id" : 2 }
+Response | { "user_id" : "599", "name" : "John Heng", ...}
+