web dev essentials

web.md

Web

Postgre

• Install

sudo apt update
sudo apt install postgresql postgresql-contrib

• Create db

sudo -u postgres createdb db_name

• Shell

sudo -u postgres psql -d db_name

• User

# Create user
create user test with password 'password';

# Grant permission

GRANT ALL PRIVILEGES ON DATABASE db_name to user_name;z

• Commands

# Tables list
\dt

# Users list
\du

# Show databases
\l

# Connect to db
\c db_name

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Node

Get Node

wget https://nodejs.org/dist/v12.18.3/node-v12.18.3-linux-x64.tar.xz

Unpack

tar -xf node.tar.xz

Set path

nano ~/.bashrc
export PATH=$PATH:/root/node/bin

Processes

npm i -g nodemon
npm i -g pm2

Node permission error

// sh: 1: node: Permission denied

npm config set user 0
npm config set unsafe-perm true

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SQL

Install

sudo apt update
sudo apt install mysql-server
sudo mysql_secure_installation

Fix Permissions

#login as sudo
sudo mysql

# give permission
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

Import SQL

mysql -u username -ppassword database_name < demo.sql

Export SQL

mysqldump -u username -p database_name > demo.sql

Export Format Error

# Find
ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_520_ci;
# in .sql file, and swap it with
ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci;

Node

npm i mysql

var mysql = require('mysql');
const util = require('util');

var connection = mysql.createConnection({
    host: process.env.MYSQLHOST,
    user: process.env.MYSQLUSER,
    password: process.env.MYSQLPASSWORD,
    database: process.env.MYSQLDB
});

exports.query = util.promisify(connection.query).bind(connection);

// await query('select * from users')

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Telegram

const noti_bot = require('noti_bot');
const notifyTelegram = noti_bot.telegram;
let TELEGRAM_BOT_TOKEN = "";
let TELEGRAM_TARGET_CHAT_ID = "";
notifyTelegram("hello bot", TELEGRAM_BOT_TOKEN, TELEGRAM_TARGET_CHAT_ID)

Get the list of updates for your BOT:

https://api.telegram.org/bot<YourBOTToken>/getUpdates

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Sqlite

 PRAGMA journal_mode=WAL

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