DEV Community: Shubham Athawane

Referral_template for Linkedin

Shubham Athawane — Sat, 01 Apr 2023 14:15:43 +0000

Referral_template

Template which I followed for asking referrals to people on LinkedIn .

"Hi { name of the person }

Hope you are doing well . Recently I came across an opening in { company name } for { role } for { year of graduation } grads .

The job id for the same is { job id } .

It would be great if you could provide me a referral for the same .

Why me?

-> { Mention all your achievements }

-> { If applying for technical roles try to mention about your projects, coding profiles , ranks }

-> { Achievements should be mentioned in bulleted format}

-> {Achievements should be one liner . Please don't try explaining everything in a paragraph manner}

I have attached my resume for the same .

Hope to hear from you soon.

Thanks

Would love if someone could add more pointers to this .

How to connect Nodejs to Mongodb Database (Two methods)

Shubham Athawane — Thu, 16 Feb 2023 11:56:31 +0000

Node.js is an open-source and cross-platform runtime environment built on Chrome’s V8 JavaScript engine for executing JavaScript code outside of a browser.

MongoDB, the most popular NoSQL database, is an open-source document-oriented database. The term ‘NoSQL’ means ‘non-relational’.

So let’s come on the matter, We will connect our NodeJS app with MongoDB using two methods:

With Localhost MongoDB compass
With MongoDB Atlas [online database]

Prerequisites:

NodeJS and any package manager [npm / yarn]
MongoDB Compass
Any Code Editor

Method 1: With Localhost MongoDB compass

Step 1: Initialise the Node in your project Directory:

npm init

Step 2: Create an Index.js file in the initialize project directory:

touch index.js

Step 3: Installing Mongoose, express, and nodemon Library. Write the below command in the terminal to install all of it:

npm install express mongoose nodemon

Project Structure: Your folder structure will look like this:

Folder Structure

Step 4: Configure the package.json file to add Nodemon

Inside the script, add Nodemon to start the script, so that you don't need to start the server again and again!
It will automatically start the server after changes are made in the Index.js file

// package.js
"start": "nodemon index.js",

After all installation and changes, your 'package.json' file should look like this:

//package.json
{
    "name": "node-mongodb-connection",
    "version": "1.0.0",
    "description": "",
    "type": "module",
    "main": "index.js",
    "scripts": {
        "start": "nodemon index.js",
        "test": "echo \"Error: no test specified\" && exit 1"
},
    "keywords": [],
    "author": "",
    "license": "ISC",
    "dependencies": {
        "dotenv": "^16.0.2",
        "express": "^4.18.1",
        "mongoose": "^6.5.4",
        "nodemon": "^2.0.19"
    }
}

Step 5: Import all packages and create an express instance, In the index.js:

const express = require('express')
const mongoose = require('mongoose')

Create the instance of the express app

const app = express();

Allocate the port to your express app

port = 3001

NOTE: Although it’s not a good practice to directly show your port [you can use dotenv library to hide your credentials].

We’ve allocated the port, Now make the port listen to the requests by passing a port parameter to the app.listen() method:

app.listen(port, (req, res) => {
    console.log(`Server is running on port ${port}`);
})

Step 6: Creating a mongoose connection:

Create a variable URL to store the local database URL. In index.js:

const URL = "mongodb://localhost:27017/node_mongodb_connection"

Now use this URL variable with mongoose.connect() method:

mongoose
    .connect(URL, {
        config: { autoIndex: true },
    })
    .then(console.log("Database Connected!"))
    .catch((err) => console.log(err));

Final Code: Your index.js file will look like this:

Javascript

const express = require("express");
const mongoose = require("mongoose");

const app = express();
const URL = "mongodb://localhost:27017/node_mongodb_connection"
const port = 3001;

// added additional code here

app.use(express.json());
app.use(express.urlencoded({ extended: true }));
mongoose.set("strictQuery", false);

// Database connectivity
mongoose
    .connect(port, {
        useNewUrlParser: true,
        useUnifiedTopology: true,
    })
    .then(() => console.log("DB connected.."))
    .catch((err) => console.error(err));

// Listening on port 3001
app.listen(URl, (req, res) => {
    console.log(`Server is running on ${port}`);
});

Here we pass the useNewUrlParser: true. to mongoose.connect() to avoid the DeprecationWarning.

Step 7: Finally, run your app

Run your app using the terminal using:

npm start

Congratulations! You have successfully connected the NodeJS app to the MongoDB database

Method 2: Using an online MongoDB database

In method 1 we have connected the node app with the local database. Here we have used MongoDB local database, But when it comes to hosting your app on the web local database won't work.

So, let's see how to connect the node app with the MongoDB atlas, it's pretty easy and simple:

Step 1: Creating MongoDB Database Cloud Cluster:

Go to MongoDB. website, Create an account if you don't have one, and then sign in
Create a free instance of the atlas
After creating the cluster, Move to the Home screen. On the Home screen of Atlas click on New Project:

altas home screen

Create your Atlas Cluster and get URI for connection

Now you just need to replace the link we copied from the MongoDB atlas with our old local host link:

Instead of:

const URL = "mongodb://localhost:27017/node_mongodb_connection"

We will use:

const URL  = "mongodb-srv://project-name:password@cluster0.gkcptov.mongodb.net/?
retrywrites=true&w=najority"

Replace the project-name and password field with your own project-name and password.

Final Code: New Index.js will look like this:

Javascript

const express = require("express");
const mongoose = require("mongoose");

const app = express();
const URL = "mongodb-srv://project-name:password@cluster0.gkcptov.mongodb.net/?
retrywrites = true & w=najority"
const port = 3001;

// added additional code here

app.use(express.json());
app.use(express.urlencoded({ extended: true }));
mongoose.set("strictQuery", false);

// Database connectivity
mongoose
    .connect(port, {
        useNewUrlParser: true,
        useUnifiedTopology: true,
    })
    .then(() => console.log("Atlas DB connected.."))
    .catch((err) => console.error(err));

// Listening on port 3001
app.listen(URl, (req, res) => {
    console.log(`Server is running on ${port}`);
});

Now Run your node application using:

npm start

Connected to atlas

Atlas DB connected! You have successfully connected the NodeJS app to the MongoDB database

Remember: You need to add your IP to the atlas whenever it gets reset.

Windows Run Commands

Shubham Athawane — Thu, 18 Aug 2022 13:05:03 +0000

Helpful run commands

%temp% -- to retrive temporory data and clean it
msconfig -- configure your services
msinfo32 -- get total information about yout device (software/hardware)
dxdiag -- info about device hardware
dfrgui -- fragment your drives
cleanmgr -- cleaning the storage
mrt- microsoft - detect virus and malware using mrt
services.msc
winver -- view yout windows version
prefetch
recent-- see your recent files
regedit -- edit the registry
temp -- temporary files

Tips and Tricks

JavaScript 8 Tips and Tricks To write less JavaScript 🙂

Shubham Athawane — Tue, 09 Aug 2022 17:03:00 +0000

1. Declaring Variables

Longhand

let firstName;
let lastName;
let surName = "beast";

Shorthand

let firstName, lastName, surName = "beast";

2. Ternary Operators

Longhand

let answer, value = 15;

if(value%2 = 0)
{
    answer = "Number is even";
}else{
    answer = "Number is not even";
}

Shorthand

let answer = value&2 = 0 ? "Number is even" : "Number is not even"

3. Ternary Short For-Loop

Longhand

const languages = ["html","css","js"];

for(let i = 0;i < language.length;i++){
    const languages = languages[i];
    console.log(languages);
}

Shorthand

for(let languages of languages)console.log(languages);

4. Template Literals

Longhand

const fullName = "codingBeast";
const timeOfDay = "afternoon";

const greeting = "Hello" + fullName + ", I wish you a good" + timeOfDay + "!";

Shorthand

const greeting = `Hello ${fullName}, I wish you a good ${timeOfDay}`;

5. Assignment Operator

Longhand

a = a+b;
a = a-b;

Shorthand

a += b;
a -= b;

6. Object Array Notation

Longhand

let arr = new Array();
arr[0] = "html"
arr[1] = "css";
arr[2] = "js";

Shorthand

let arr = ["html","css","js"];

7. Arrow Function

Longhand

function addition(a,b){
    console.log("addition",a + b);
}

Shorthand

addition = (a,b) => console.log("addition", a + b);

8. Identical key and Values

Longhand

const userDetails = {
    name: name,     // key:value
    email: email,
    age: age,
    location: location,
};

Shorthand

Important C Programs

Shubham Athawane — Fri, 25 Mar 2022 11:32:52 +0000

1. Leap Year Program

Leap years are the year where an extra, or intercalary, days is added to the end of the shortest month, February.

If a year is exactly divisible by 4 and not divisible by 100 then it’s a Leap year. Else if year is exactly divisible by 400 then its’ Leap year. Else it’s a Common year.

#include <stdio.h>

int main()
{
    int year;
    scanf("%d", &year);
    if ((year % 400 == 0) || (year % 4 == 0 && year % 100 == 0))
    {
        printf("%d is a leap year", year);
    }
    else
    {
        printf("%d is not leap year", year);
    }

    return 0;
}

2. Factorial Program

Factorial of number(n) is the product of all positive descending integers. Factorial of n is denoted by N!

Example : 5! = 5*4*3*2*1 = 120

// Factorial in C without recursion..
#include <stdio.h>

int main()
{
    int num, i;
    long int fact;
    printf("Enter an Integer Number : ");
    scanf("%d", &num);

    fact = 1;

    for (i = num; i >= 1; i--)
    {
        fact *= i;
    }
    printf("Factorial of %d is %ld ", num, fact);

    return 0;
}

3. Reverse Numbers.

The logic Used to reverse a number is also Used in palindrome, Armstrong or to find sum of digits of a number with a little change in it.

// Reverse a Number in C
#include <stdio.h>

int main()
{
    int n, reverse = 0, rem;
    printf("Enter a number : ");
    scanf("%d", &n);

    while (n != 0)
    {
        rem = n % 10;
        reverse = reverse * 10 + rem;
        n /= 10;
    }
    printf("Reversed Number: %d", reverse);
    return 0;
}

4. 3 Ways to Swap two numbers:

//3 ways to swap the numbers in c
#include <stdio.h>

int main()
{
    int num1, num2;
    int temp;

    printf("Etner First Number : ");
    scanf("%d", &num1);
    printf("Etner Second Number : ");
    scanf("%d", &num2);

    // Using 3rd variable
    temp = num1;
    num1 = num2;
    num2 = temp;
    printf("\nUsing 3rd Variable : ");
    printf("\nFirst Number %d and Second Number %d", num1, num2);

    // Without using 3rd variable
    num1 = num1 + num2;
    num2 = num1 - num2;
    num1 = num1 - num2;
    printf("\nWithout using 3rd Variable : ");
    printf("\nFirst Number %d and Second Number %d", num1, num2);

    // using XOR operator
    num1 = num1 ^ num2;
    num2 = num2 ^ num1;
    num1 = num1 ^ num2;
    printf("\nusing XOR Operator : ");
    printf("\nFirst Number %d and Second Number %d", num1, num2);

    return 0;
}

5. Perfect Number Program

A perfect number is a positive integer that is equal to the sum of it’s positive divisors, excluding the number itself.

Example: 6 (1+2+3) = 6

// C Program to check whether the given number is th Perfect Number
#include <stdio.h>

int main()
{
    int num, rem, sum = 0, i;
    printf("Enter a number : ");
    scanf("%d", &num);

    // find all divisors and add them
    for (i = 1; i < num; i++)
    {
        rem = num % i;
        if (rem == 0)
        {
            sum += i;
        }
    }

    if (sum == num)
    {
        printf("%d is a Perfect Number : ", num);
    }
    else
    {
        printf("%d is not a Perfect Number : ", num);
    }
    return 0;
}

6. Fibonacci Series Without recursion:

In case of Fibonacci series, next number is the sum of previous two numbers for example 0,1,1,2,3,5,8,13 etc. The first two numbers of Fibonacci series are 0 and 1.

// Fibpnacci Series withou recursion:
#include <stdio.h>
int main()
{
    int n1 = 0, n2 = 1, n3, i, number;
    printf("Enter the number of elements : ");
    scanf("%d", &number);
    printf("\n%d %d", n1, n2); // printing 0 and 1;
    // loop starts from 2 because 0 and 1 are already printed
    for (i = 2; i < number; i++)
    {
        n3 = n1 + n2;
        printf(" %d", n3);
        n1 = n2;
        n2 = n3;
    }
    return 0;
}

7. Fibonacci Series using recursion:

Many people prefers to code some programs like factorial or Fibonacci using recursion method. for those you don’t know about recursion, “When a function calls itself it is call recursion”.

// Fibonacci series program in c using recursion
#include <stdio.h>
void printfFibonacci(int n)
{
    static int n1 = 0, n2 = 1, n3;
    if (n > 0)
    {
        n3 = n1 + n2;
        n1 = n2;
        n2 = n3;
        printf("%d ", n3);
        printfFibonacci(n - 1);
    }
}
int main()
{
    int n;
    printf("Enter the number of element : ");
    scanf("%d", &n);
    printf("Fibonacci Series : ");
    printf("%d %d ", 0, 1); // Printing 0 and 1
    printfFibonacci(n - 2); // n-2 because 2 numbers are already printed

    return 0;
}

8. Prime Numbers Program

Prime number is a number that is greater than 1 and divided by 1 or itself.

Example : 2,3,5,7,13 etc.

Fact: 2 is the only even prime number.

// C Program to find prime number
#include <stdio.h>
int main()
{
    int n, i, m = 0, flag = 0;
    printf("Enter the number to check prime : ");
    scanf("%d", &n);
    m = n / 2;
    for (i = 2; i <= m; i++)
    {
        if (n % i == 0)
        {
            printf("Number is not prime");
            flag = 1;
            break;
        }
    }
    if (flag == 0)
    {
        printf("Number is prime");
    }
    return 0;
}

9. Palindrome Program

A palindrome number is a number that is same after reverse.

For example : 121, 34543, 343,131,48984 are the palindrome numbers.

// C Program to find palindrome
#include <stdio.h>
int main()
{
    int n, r, sum = 0, temp;
    printf("Enter the number : ");
    scanf("%d", &n);
    temp = n;
    while (n > 0)
    {
        r = n % 10;
        sum = (sum * 10) + r;
        n = n / 10;
    }
    if (temp == sum)
    {
        printf("Number is palindrome");
    }
    else
    {
        printf("Number is not palindrome");
    }
    return 0;
}

10. Armstrong Number:

Armstrong number is a number that is equal to the sum of cubes of it’s digits. For example 0,1,153,370, and 407 are the Armstrong numbers.

Example : 153 = (1*1*1)+(5*5*5)+(3*3*3)

// Program to check Armstrong Number in c.
#include <stdio.h>
int main()
{
    int n, r, sum = 0, temp;
    printf("Enter the number : ");
    scanf("%d", &n);
    temp = n;
    while (n > 0)
    {
        r = n % 10;
        sum = sum + (r * r * r);
        n = n / 10;
    }
    // Check sum of cubes is equal to original no.
    if (temp == sum)
    {
        printf("%d Number is armstrong", temp);
    }
    else
    {
        printf("%d Number is not armstrong", temp);
    }
    return 0;
}

How to become a Blockchain Developer ?

Shubham Athawane — Sun, 06 Mar 2022 18:40:23 +0000

Who is a Blockchain Developer ?

blockchain developer is a developer that takes care of optimizing and developing blockchain-related dApps, smart contracts, protocols, and architecture.

It is a responsible position which requires attention to detail, knowledge, and ability to overcome challenges.

Types of Blockchain Developers

Core Blockchain Developers

The core blockchain developers are responsible for architecture development.

Blockchain Software Developer

Blockchain Software Developer works differently. His role is to develop and implement the blockchain using the designs created by the core blockchain developers.

Technical Skills Required

Understanding blockchain architecture
Data Structures
Smart contract development
Basic understanding of cryptography

How to become a Blockchain developer ?

Finally , let’s dive into the steps to become a blockchain developer.

Step 1: Learn basics

Learn about what is decentralization, the use of consensus, also dive deep into cryptography. L
Lastly, you should learn about the blockchain ecosystem.
- Enterprise blockchain platforms
- Blockchain as a Service(BaaS) such as Hyperledger, quorum, Corda and Ethereum Enterprise
- Learn about popular dApps.

Step 2: Learn how the blockchain process works.

With basics complete, now you need to get familiar with real-world implementation.
To get started, start by working through basic cryptocurrency, you will be able to appreciate what blockchain has to offer.
Remember, cryptocurrency is just one use-case of blockchain. It is the first use-case of blockchain.
By going through the whole process, you can understand how cryptocurrency, one of the most significant use-cases of blockchain works.

Step 3: Start coding - Learn from blockchain tutorials

it is now time to dive deep into coding.

For beginners, I would learning Solidity. It will help you create and developer dApps and smart contracts on Ethereum blockchain.

Create a simple block
Create a blockchain out of it
Understand what is genesis block and implement it
Adds the blocks to the blockchain
Validate the chain
Use it by doing test runs.

If you do everything correct, you will have a basic
working blockchain!

Step 4: Learn Smart Contracts

A smart contract is also one of the vital blockchain concepts that you need to learn.

You can use it to automate or add functionality to your dApps.

Step 5: Read Blockchain Related Content

Keep reading blockchain-related content. Many websites offer high-qualíty, blockchain content. I recommend checking out BlockGeeks and **101Blockchains.com.**

Step 6: Keep improving !

There is no end to learn!

How to become a Blockchain Developer ?

Shubham Athawane — Sun, 06 Mar 2022 17:45:58 +0000

Who is a Blockchain Developer ?

blockchain developer is a developer that takes care of optimizing and developing blockchain-related dApps, smart contracts, protocols, and architecture.

It is a responsible position which requires attention to detail, knowledge, and ability to overcome challenges.

Types of Blockchain Developers

Core Blockchain Developers

The core blockchain developers are responsible for architecture development.

Blockchain Software Developer

Blockchain Software Developer works differently. His role is to develop and implement the blockchain using the designs created by the core blockchain developers.

Technical Skills Required

Understanding blockchain architecture
Data Structures
Smart contract development
Basic understanding of cryptography

How to become a Blockchain developer ?

Finally , let’s dive into the steps to become a blockchain developer.

Step 1: Learn basics

Learn about what is decentralization, the use of consensus, also dive deep into cryptography. L
Lastly, you should learn about the blockchain ecosystem.
- Enterprise blockchain platforms
- Blockchain as a Service(BaaS) such as Hyperledger, quorum, Corda and Ethereum Enterprise
- Learn about popular dApps.

Step 2: Learn how the blockchain process works.

With basics complete, now you need to get familiar with real-world implementation.
To get started, start by working through basic cryptocurrency, you will be able to appreciate what blockchain has to offer.
Remember, cryptocurrency is just one use-case of blockchain. It is the first use-case of blockchain.
By going through the whole process, you can understand how cryptocurrency, one of the most significant use-cases of blockchain works.

Step 3: Start coding - Learn from blockchain tutorials

it is now time to dive deep into coding.

For beginners, I would learning Solidity. It will help you create and developer dApps and smart contracts on Ethereum blockchain.

Create a simple block
Create a blockchain out of it
Understand what is genesis block and implement it
Adds the blocks to the blockchain
Validate the chain
Use it by doing test runs.

If you do everything correct, you will have a basic
working blockchain!

Step 4: Learn Smart Contracts

A smart contract is also one of the vital blockchain concepts that you need to learn.

You can use it to automate or add functionality to your dApps.

Step 5: Read Blockchain Related Content

Keep reading blockchain-related content. Many websites offer high-qualíty, blockchain content. I recommend checking out BlockGeeks and **101Blockchains.com.**

Step 6: Keep improving

There is no end to learn

What is React-Redux ?

Shubham Athawane — Tue, 01 Mar 2022 05:45:59 +0000

Predictable state container

Redux is a predictable state container for JavaScript apps
Helps you write apps that behaves consistently, run in different environments, and are easy to test.
Offers live code editing combined with a time traveling debugger.
Can be use with React, angular , or any other view library.
Redux is tiny(roughly 2kb), but has a large ecosystem of addons available.

Central store

With Redux, application state is kept in a store, from which any component can access any state it needs
State is kept in a single place, improving predictability and traceability
In React, for example, state has to live in the parent component to share data among siblings
And so, sharing state between components that are far away from each other is hard state will have to be lifted until a common ancestor is found
Redux solves this issue by providing a central store holding the entire application state

Features of Redux

Predictable - Redux helps you write apps that behave consistently
Centralized application state and logic enables powerful capabilities, such as undo/redo, state persistence, etc.
Debuggable - Redux DevTools make it easy to trace state, changes
Time-travel debugging is also possible
Flexible - Redux works with any UI layer

Want to check example ? click here

Write these C/C++ Program before going to Interview.

Shubham Athawane — Sat, 25 Dec 2021 06:30:37 +0000

While-loop

WAP - To check string is Palindrome or not
WAP - To check number is Armstrong or not.
WAP - To check number is perfect or not.
WAP - To check number is prime or not

WAP - To find number Factorial.
WAP - To find number Factorial or not
WAP - To print Fibonacci & and Tribonacci.
WAP - To find prime number between the number rang
WAP - To calculate area of circle, (Square, rectangle and triangle )
WAP - To check Leap year or not.
WAP - To swap to numbers.
WAP - To swap to numbers without using third variable.

Array

WAP - To sort array element in ascending and descending order.
WAP - To insert element at beginning, ending and any position of array.
WAP - To print array element in reverse order.
WAP - To find maximum and minimum element of array (smallest, largest)
WAP - To print 2d array matrix transport matrix.
WAP - To print mirror matrix
WAP - To swap two matrix.

WAP - To print palindrome string
WAP - To convert temperature Celsius to Fahrenheit and vice-versa
WAP - To add two number using pointer.
WAP - To print 5 student records suing structure and union.
WAP - To calculate total and average marks of 5 subjects (struct)
WAP - to calculate tax

Conditions : if ≤1000 then “No Tax”

if > 1000 && ≤ 100000 then “10%” tax

if > 100000 then “25%” tax
WAP - To add every element from array.
WAP - To search array elements with appropriate location

Patterns

Pattern 1

*
* *
* * *
* * * *
* * * * *

Pattern 2.

* * * * * * 
* * * * * * 
* * * * * * 
* * * * * *

Pattern 3

           *
         *   *
       *   *   *
     *   *   *   *
   *  *    *   *   *
 *   *   *   *   *   *

Pattern 4

1 
2 3
4 5 6
7 8 9 10
11 12 13 14

Pattern 5.

* * * * * * * * *
  * * * * * * *
    * * * * *
      * * *
        *

Pattern 6: half pyramid of alphabets

A
B B
C C C
D D D D
E E E E E

MySQL Cheat sheet

Shubham Athawane — Fri, 24 Dec 2021 15:36:50 +0000

Creating tables 📑

CREATE TABLE BookHistory (
    Auther VARCHAR(129),
    title VARCHAR(129),
    btype VARCHAR(129),
    year CHAR(4)
);

To drop table column

ALTER TABLE tableName DROP column-Name;
ex.
ALTER TABLE BookHistory DROP Auther;

How to delete Data from a MySQL table ?

// Delete Statement is used to delete data, 

DELETE FROM table_name WHERE column_name = VALUE
EX. 
DELETE FROM BookHistory WHERE title = 'JungleBook'

Inserting Value into Table.

INSERT INTO table_name (Column1, Column2, Column3 ) VALUES (value1, value3, value3);
EX. 
INSERT INTO BookHistory (Author, title, btype, year) VALUES ("James Camron", "Avatar", "Adventure", 2006);

Update column name.

ALTER TABLE table_name RENAME COLUMN old_col_name TO new_col_name;
EX. 
ALTER TABLE BookHistory RENAME COLUMN btype TO Book_type;

Add new column in table

ALTER TABLE table_name ADD column_name DATATYPE;
EX. 
ALTER TABLE BookHistory ADD price INT(4);

The Select Command : DQL- DATA QUERY LANGUAGE Command.

Used to visualize the table content.

SELECT * FROM table_name;
EX.
SELECT * FROM BookHistory;

// It will show all data present inside the BookHistory table

We can use SELECT command to retrieve specific data from the table using WHERE clause . Like below

SELECT * FROM table_name WHERE condition;
EX.
SELECT * FROM BookHistory WHERE Book_type = "hacking";

MySQL numeric Data types

MySQL has numeric data types for Integer, Fixed-point, Floating-Point and bit etc.

*Numeric can be singed or unsinged

1. TINYINT 6. FLOAT

2. SMALLINT 7. DOUBLE

3. MEDIUMINT 8. BIT

4. INT

5. BIGINT
String Data type.

1. CHAR 5. TINYBLOB

2. VARCHAR 6. MEDIUMBLOB

3. BINARY 7. LONGBLOB

4. VARBINARY
Temporal Data Types in MySQL
1. DATE - A date value in 'CCYY-MM-DD'
2. TIME- Time in 'HH:MM:SS'
3. DATETIME - Date-Time - 'CCVV-MM-DD HH:MM:SS'
4. TIMESTAMP - 'CCVV-MM-DD' HH:MM:SS
5. YEAR - CCYY or YY
Create user in MySQL

1. TINYINT	6. FLOAT
2. SMALLINT	7. DOUBLE
3. MEDIUMINT	8. BIT
4. INT
5. BIGINT

1. CHAR	5. TINYBLOB
2. VARCHAR	6. MEDIUMBLOB
3. BINARY	7. LONGBLOB
4. VARBINARY

CREATE USE 'user-name' IDENTIFIED BY 'sample-password';

What are the "VIEWS" ?

→ In MySQL , A view consists of a set of rows that returned if particular query is executed.

→ It also known as "Virtual Table"

→ Advantages : Simplicity, security, not consume any memory, maintainability.

How to you create & Execute VIEWS in MySQL ?

→ We can create views using the CREATE VIEW Statement;

-> A view is table in database that has no values, The views are created by joining one or more tables.
-> Syntax for creating Views
```
CREATE [or REPLACE] VIEW view_name AS SELECT columns FROM TABLES [ WHERE CONDITION ]
```
SELECT AND command.

SELECT * FROM cust_tbl WHERE f_name = "shubham" AND cust_id > 3;

Truncate : It removes complete data without removing it’s structure. It is a DDL Command

TRUNCATE TABLE table_name;
EX.
TRUNCATE TABLE BookHistory;

Update Command in MySQL.

UPDATE 'table_name' SET 'column_name' = 'new_value' [WHERE CONDITION];
EX.
UPDATE BookHistory SET 'Auther' = 'James Bond' WHERE Auther = "JB";

BETWEEN : Get values between particular condition.

SELECT * FROM cus_tbl WHERE ID = 8 AND 11;

Find version of installed MySQL.

Type Following Command.

SHOW VARIABLES LIKE "%version%";

ENUM and SET.

ENUM data type is used in the MySQL datatypes to select any one value from the predefined list. Ex

CREATE DATABASE newEnum;
CREATE TABLE Clients (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50), 
    memberShip ENUM('silver', 'gold', 'Diamond'),
    interested SET('Movie', 'Music', 'concert');
)

Cannot set multiple in ENUM but we can set multiple values in SET.

What is different between Primary key and Foreign Key ?

-> The database table uses Primary key to identify each row uniquely, It is necessary to declare a primary key on those tables that require tp create a relationship among them. - One or More field of table can be declared as primary key

-> When primary key of any table is used in another table as the primary key or anther field for making a database relation then it is called Foreign Key.

-> Primary Key : Identified a record whereas foreign key refers the primary key of another tables. Primary key never accepts not null value. But Foreign key accepts null value.

Filter duplicate values.

-> A DISTINCT keyword is used to identify the duplicate data from table while retrieving the records. EX.

SELECT * FROM items

output:

id	name	type	brand	man_id
1	samsung	mobile	samsung	1
2	iPhone	mobile	apple	2
3	Sony	TV	Sony	3

Using DISTINCT Keyword

SELECT DISTINCT type FROM items;

output:

type
mobile
TV

Which statement is used in a select query statement for partial matching ?

→ REGEXP and LIKE statement can be used in a select query for partial matching.

REGEXP : used to Search records bases on the pattern matching
LIKE : Is used to search any record by matching string at beginning or end or middle of particular filed value.

Ex. 1. REGEXP (Search records start with ‘S’);

SELECT * FROM BookHistory WHERE name REGEXP "^s";

Ex. 2. LIKE

SELECT * FROM BookHistory WHERE name LIKE "A%";

Rename Table

RENAME TABLE table_name TO new_table_name;
EX.
RENAME TABLE items TO Products;

Retrieve a portion of any Column value by using select Query ?

→ * SUBSTR() Function is used to retrieve the portion of any column. EX

OR we can we ‘SUBSTRING’ keyword

SELECT SUBSTR(name, 1, 5) FROM Products;

output:

Samsu
iPhon
Sony

Calculate Sum of any Column of table ?

→ SUM() Function is used to calculate the sum of any column. EX.

SUM(DISTINCT expression)
EX.
SELECT SUM(Price) as total FROM Products;

output:

total
2109.00

The Practical Approach

Fetch FIRST_NAME from worker table.

SELECT First_name as worker_name from Woker;

//will return all first_name 's

Fetch FIRST_NAME as Upper Case

SELECT upper(First_name) FROM Worker

// Will return all name in upper case

Fetch unique Values from Department

SELECT DISTINCT department FROM Worker;

output :

department
HR
ADMIN
ACCOUNT

Find position of alphabets (”a”) in first_name column ‘Amitabh’ from worker.

SELECT INSTR(first_name, BINARY'a') FROM worker WHERE first_name = "Amitabh";

output :

INSTR( first_name, BINARY ’a’ )
5

Remove white Spaces
1. RTRIM : To remove white spaces from right side. EX
```
SELECT RTRIM(first_name) FROM Worker;
```
b. LTRIM : To remove white spaces from left side. EX
```
SELECT LTRIM(Department) FROM Worker;
```
Query to print first_name and salary from worker table into a single column NAME_SALARY

→ We use CONCAT() keyword to get combined result from two or more tables. EX

SELECT CONCAT(first_name, "=" , Salary) AS 'NAME_SALARY' FROM Worker;

Query to print all worker details from worker table order by First_Name Ascending.

SELECT * FROM Worker ORDER BY First_Name ASC;

Print details for worker with First_name as ‘Shubham’ and ‘NICK’ from worker table.

SELECT * FROM Worker WHERE First_Name In('Shubham', 'NICK');

Query to fetch the count of employee working in the department ‘admin’.

→ The count function return cunt of given queries : EX.

SELECT COUNT(*) FROM Worker WHERE Department = 'Admin';

output :

count(4)
4

AGGREGATE FUNCTIONS : -

SQL Aggregate functions is used to perform calculations on multiple row of a single column of a table it return single value.

COUNT()
SUM()
AVG()
MAX()
MIN()

COUNT()

→ Count the number of rows in database; It uses function COUNT(*) that return all rows

SELECT COUNT(*) FROM Worker WHERE Department = 'Admin';

count(4)
4

SUM()

→ SUM() Function is used to calculate the sum of all selected columns. it only work on numeric values. Syntax: sum();

SELECT SUM(salary) FROM Worker;
or 
SELECT

AVG()

→ Used to calculate average value of the numeric type. AVG function return the average of all non-null values. Syntax: AVG();

SELECT Avg(salary) FROM Workder;

MAX():

→ Max function used to find the maximum value of a certain column . This function determines the largest value of all selected values of column. Syntax: MAX();

SELECT MAX(SALARY) FROM Worker;

MIN();

→ MIN used to find minimum value of a certain column. this function determines the smallest value of all selected of a column.

SELECT MIN(SALARY) FROM Worker

Joins

Two relations

Personal
Professional

select * from personal;

+----+----------+---------+-----------+
| id | name     | address | contact   |
+----+----------+---------+-----------+
| 10 | ankit    | kapali  | 838405939 |
| 20 | ankush   | kapali  | 835403953 |
| 30 | akhilesh | mango   | 335502953 |
| 40 | altaf    | sakchi  | 985402953 |
+----+----------+---------+-----------+

select * from professional;

+------------+-------+------+
| work       | dep   | id   |
+------------+-------+------+
| teacher    | bca   |   20 |
| docktor    | mbbs  |   40 |
| teacher    | mba   |   50 |
| programmer | java  |   60 |
| cashier    | icici |   10 |
+------------+-------+------+

1. Natural Join

select * from personal natural join professional;

Output:

+----+--------+---------+-----------+---------+-------+
| id | name   | address | contact   | work    | dep   |
+----+--------+---------+-----------+---------+-------+
| 10 | ankit  | kapali  | 838405939 | cashier | icici |
| 20 | ankush | kapali  | 835403953 | teacher | bca   |
| 40 | altaf  | sakchi  | 985402953 | docktor | mbbs  |
+----+--------+---------+-----------+---------+-------+

2. Inner Join

select name,contact,dep from personal inner join professional on [personal.id](http://personal.id/) = [professional.id](http://professional.id/);

output:


+--------+-----------+-------+
| name   | contact   | dep   |
+--------+-----------+-------+
| ankit  | 838405939 | icici |
| ankush | 835403953 | bca   |
| altaf  | 985402953 | mbbs  |
+--------+-----------+-------+

3. Cross Join

select * from personal cross join professional;

output:

+----+----------+---------+-----------+------------+-------+------+
| id | name     | address | contact   | work       | dep   | id   |
+----+----------+---------+-----------+------------+-------+------+
| 10 | ankit    | kapali  | 838405939 | teacher    | bca   |   20 |
| 20 | ankush   | kapali  | 835403953 | teacher    | bca   |   20 |
| 30 | akhilesh | mango   | 335502953 | teacher    | bca   |   20 |
| 40 | altaf    | sakchi  | 985402953 | teacher    | bca   |   20 |
| 10 | ankit    | kapali  | 838405939 | docktor    | mbbs  |   40 |
| 20 | ankush   | kapali  | 835403953 | docktor    | mbbs  |   40 |
| 30 | akhilesh | mango   | 335502953 | docktor    | mbbs  |   40 |
| 40 | altaf    | sakchi  | 985402953 | docktor    | mbbs  |   40 |
| 10 | ankit    | kapali  | 838405939 | teacher    | mba   |   50 |
| 20 | ankush   | kapali  | 835403953 | teacher    | mba   |   50 |
| 30 | akhilesh | mango   | 335502953 | teacher    | mba   |   50 |
| 40 | altaf    | sakchi  | 985402953 | teacher    | mba   |   50 |
| 10 | ankit    | kapali  | 838405939 | programmer | java  |   60 |
| 20 | ankush   | kapali  | 835403953 | programmer | java  |   60 |
| 30 | akhilesh | mango   | 335502953 | programmer | java  |   60 |
| 40 | altaf    | sakchi  | 985402953 | programmer | java  |   60 |
| 10 | ankit    | kapali  | 838405939 | cashier    | icici |   10 |
| 20 | ankush   | kapali  | 835403953 | cashier    | icici |   10 |
| 30 | akhilesh | mango   | 335502953 | cashier    | icici |   10 |
| 40 | altaf    | sakchi  | 985402953 | cashier    | icici |   10 |
+----+----------+---------+-----------+------------+-------+------+

4. Left outer join

select name, address, dep, work from personal left outer join professional on [personal.id](http://personal.id/) = [professional.id](http://professional.id/);

output:

+----------+---------+-------+---------+
| name     | address | dep   | work    |
+----------+---------+-------+---------+
| ankush   | kapali  | bca   | teacher |
| altaf    | sakchi  | mbbs  | docktor |
| ankit    | kapali  | icici | cashier |
| akhilesh | mango   | NULL  | NULL    |
+----------+---------+-------+---------+

5. Right outer join

select name, address, dep, work from personal right outer join professional on [personal.id](http://personal.id/) = [professional.id](http://professional.id/);

Outupt:

+--------+---------+-------+------------+
| name   | address | dep   | work       |
+--------+---------+-------+------------+
| ankit  | kapali  | icici | cashier    |
| ankush | kapali  | bca   | teacher    |
| altaf  | sakchi  | mbbs  | docktor    |
| NULL   | NULL    | mba   | teacher    |
| NULL   | NULL    | java  | programmer |
+--------+---------+-------+------------+

React-Redux How It's Works ?

Shubham Athawane — Sat, 11 Dec 2021 14:18:27 +0000

How Redux works with React ? Let's see, In this tutorial we trying to learn the concept of react-redux (for beginners), We will be creating a small increment - decrement application using react-redux, Which I think is best example to learn complex concepts like these, So let's start.

-———————————————

First of all create Your React App using npx create-react-app app-name and install following decencies :

→ npm install react-redux redux

after all installation and creating-app write in command npm start to run your application and follow the below steps : -

important note: - there is problem with numbering, So please adjust
-———————————————

Create Folder inside the src called actions, and inside the action folder create file called index.js and Inside that file we will create Actions like INCREMENT / DECREMENT , basically we will called it as What kind of action to do with and write following code inside index.js file

// .actions/index.js
export const incNumber = () => {
    return {
        type:"INCREMENT"
    }
}
export const decNumber = () => {
    return {
        type:"DECREMENT"
    }
}
export const resetNumber = () => {
    return {
        type:"RESET"
    }
}

Here in this file we have created the function which will trigged by an action using dispatch method, in this file we have created 3 functions and exported them separately using export keyword, in here inNumber() will trigger "INCREMENT" method and so on.

Create another folder in src called reducers, and inside reducers folder create file upDown.js and index.js. upDown.js we will create a functions that will change the state of our application. upDown.js file will contain following code.

This file will contain How to Do scenario.

//reducer/upDown.js
    const initialState = 0;
    // It is always better to initial our state with 0 or to initialize 
    const changeTheNumber = (state = initialState, action) => {
      switch (action.type) {
        case "INCREMENT":
          return state + 1;
        case "DECREMENT":
          return state - 1;
        case "RESET":
            return state = 0;
        default:
          return state;
      }
    };

    export default changeTheNumber;

Then inside the index.js we will import the the function ChangeTheNumber from upDown.js file and here we will use CombineReducers from redux and will create function rootReducers it is most important step , and after creating the rootReducers we'll export it, like bellow

// ..reducers/index.js
    // Imprting reducer from upDown file 
    import changeTheNumber from "./upDown";
    // Importing combineReducers object 
    import { combineReducers } from "redux";

    // Creating RootReducer 
    const rootReducer = combineReducers({
        changeTheNumber
    })

    //Exporting rootReducer
    export default rootReducer;

In this step we will create a store for our react-redux application, so we will need to install react-redux package into your application using npm install react-redux , ( ignore if you already install ) after installation write the following code inside store.js file

// src/store.js
    import { createStore } from 'redux'

    // Importing RootReducers
    import rootReducer from './reducer/index'

    //Creating Store and passing rootreducer
    const store = createStore(rootReducer, window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__());

    export default store;

and we will export that store to import inside index.js to make it global store. So let's how we can make it global store in next step.

Go to you index.js file from src, Here import store which we exported from store.js file and also import Provider from react-redux like below.

// index.js
    import React from "react";
    import ReactDOM from "react-dom";
    import "./index.css";
    import App from "./App";
    import reportWebVitals from "./reportWebVitals";
    import store from "./store";
    import { Provider } from "react-redux";

    store.subscribe(() => console.log(store.getState()));

    ReactDOM.render(
      <React.StrictMode>
        <Provider store={store}>
          <App />
        </Provider>
      </React.StrictMode>,
      document.getElementById("root")
    );

    reportWebVitals();

Your index.js file will look like this, here we have wrap our App inside and Pass the store={store} as a prop

( You can use redux devtool if you want : and add following code to work with devtool , It is optional to see reducers inside browsers but makes working with reducers easy )

store.subscribe(() => console.log(store.getState()));

Final Step : Go to your app.js file and import the functions we created inside /actions/ file such as { decNumber, incNumber, resetNumber } and create a variable which will hold the state result. we use dispatch method to trigger events like dispatch( functionName() ). after all our app.js file will look like this →

    import "./App.css";
    import {useSelector, useDispatch } from 'react-redux'
    import { decNumber, incNumber, resetNumber } from "./action";

    function App() {

      const myState = useSelector((state) => state.changeTheNumber )
      const dispatch = useDispatch();

      return (
        <div className="App">
          <h2>Increment / Decrement Counter</h2>
          <h4>Using React and Redux</h4>

          <div className="quantity">
            <button className="quantity_minus" title="Decrement" onClick={() => dispatch(decNumber())}>
              <span> - </span>
            </button>
            <input
              name="quantity"
              type="text"
              className="quantity_input"
              value={myState}
            />
            <button className="quantity_plus" title="Increament" onClick={() =>dispatch(incNumber())} >
              <span> + </span>
            </button>
            <button className="quantity_plus" title="Reset Count" onClick={() =>dispatch(resetNumber())} >
              <span> Reset </span>
            </button>

          </div>
        </div>
      );
    }

    export default App;

This is how application is looking like : -

So this is how we can implement react-redux in our react application, Hopefully you find this tutorial helpful. Thank You.

Beginners MongoDB Cheat-Sheet

Shubham Athawane — Tue, 07 Dec 2021 06:27:41 +0000

What is MongoDB ?

MongoDB is a document-oriented NoSQL database used for high valume data storage instead of using table and rows as in the traditional relational databses, MongoDB makes use of collections and documents

Then Question arises What is documents and Collections ?

Documents : Consist of key-value pairs which are the basic unit of the data in MongoDB.

Collections : Contain sets of documents and functions which is the equivalent of relational database tables

1.Enlist available databases

→ Show db

2 . To Create a new DB

→ use db-name

3 . See your current working directry

→  db

4 . Delete Database

db.mydb.drop()

5 . Create User

-> db.createUser({
    user:'admin',
    pws:'root',
    roles:["readWrite", "dbAdmin"]  
})

6 . Creating Collections

-> db.createCollection('customers');

7 . Showing Collections

-> show collections

8 . Inserting values into collections

-> db.customers.insert({first_name:"shubham", last_name:"Athawane"});

9 . View Collection Records

-> db.customers.find();
//And
-> db.customers.find().pretty();
//Note: pretty() will show you result in json formate

10 . Add new Document in Collections

->  db.customers.insert([{"first_name":"Virat", "last_name":"Kohli"},
 {"first_name":"Taylor", "last_name":"Swift"}])
// And -> $set, $inc, $unset
-> db.customers.update({first_name:"Glen"}, {$set:{age:45}})

11 . Rename Document

-> db.customers.update({first_name:"Virat"}, {$rename:{"age":"old"}})

12 . Remove document

-> db.customers.remove({first_name:"Joe"})

13 . find the matching

-> db.customers.findOne({first_name:"Joe"})

14 . Count Rows

-> db.customers.count()

15 . This is Less than/Greater than/ Less than or Eq/Greater than or Eq operators

db.customers.find({age: {$lt: 90}})
db.customers.find({age: {$lte: 90}})
db.customers.find({age: {$gt: 90}})
db.customers.find({age: {$gte: 90}})