
`AUTO_INCREMENT` facilitates the automatic generation of a unique number when inserting a new record into a table. Typically, this is applied to the `PRIMARY KEY` field, ensuring its automatic creation for each new record insertion.

# MySQL `AUTO_INCREMENT`

MySQL employs the `AUTO_INCREMENT` keyword to enable the auto-increment functionality. The default initial value for `AUTO_INCREMENT` is `1`, and it increments by `1` for each new record. 

In the `Product` table, the `Pid` column can be defined as an `AUTO_INCREMENT` `PRIMARY KEY` field using the following SQL statement: 

CREATE TABLE Product (
    Pid int NOT NULL AUTO_INCREMENT,
    ProductName varchar(255) NOT NULL,
    Quantity int,
    Price int,
    PRIMARY KEY (Pid)
);

When inserting data into the `Product` table, there is no need to specify the values for the `Pid` column.

Take a look at the following `insert` query:

INSERT INTO Product (ProductName,Quantity,Price)
VALUES ('Oats',10,200);
INSERT INTO Product (ProductName,Quantity,Price)
VALUES ('Soap',5,100);

## Code example 
To enhance our understanding of how `AUTO_INCREMENT` works, let's execute the code below and observe the output:

#!/usr/bin/env bash

mkdir -p /var/run/mysqld
chmod 777 -R /var/run/mysqld
chown -R mysql:mysql /var/lib/mysql /var/run/mysqld

# check if mysql is running before restarting it

/usr/bin/mysqld_safe &

# wait for mysql to start up
echo "Please wait for 3 seconds ..."
sleep 3
mysql -u root -Bse "DROP DATABASE IF EXISTS MovieIndustry;"
clear
# Launch MySQL
mysql < mysql.sql



-- Use the database MySQL
USE mysql;

-- Create the Product table 
CREATE TABLE Product (
    Pid int NOT NULL AUTO_INCREMENT,
    ProductName varchar(255) NOT NULL,
    Quantity int,
    Price int,
    PRIMARY KEY (Pid)
);

-- Insert into Product table 
INSERT INTO Product (ProductName,Quantity,Price)
VALUES ('Oats',10,200);
INSERT INTO Product (ProductName,Quantity,Price)
VALUES ('Soap',5,100);

-- Print the Pid and ProductName 
SELECT Pid,ProductName FROM Product;

import React from 'react';
import { shallow, configure } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';

configure({ adapter: new Adapter() });

import HelloWorld from './app';

var TestResult = function() {
    this.succeeded = false;
    this.reason = "";
    this.input = "";
    this.expected_output = "";
    this.actual_output = "";
}

export const executeTests = function() {

  var results = [];

  result = new TestResult();
  result.input = 'HelloWorld Component';
  result.expected_output = "span containing text 'Hello World'"

  let wrapper = shallow(<HelloWorld />);

  // Call your Challenge function here.

  let type = wrapper.type();
  let testSuccessful = true;
  let failureReason;

  if (type !== 'span') {
    testSuccessful = false;
    failureReason = "You need to render exactly one span HTML element";
  } else if (wrapper.props().children != "Hello World") {
     testSuccessful = false;
     failureReason = "You have rendered wrong message in your span element";
  }

  result.actual_output = wrapper.html();

  if (testSuccessful) {
    result.succeeded = true;
    result.reason = "Succeeded"
  } else {
    result.succeeded = false;
    result.reason = failureReason;
  }

  results.push(result);

  return results;
}


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How does AUTO_INCREMENT work in MySQL?

AUTO_INCREMENT generates unique, auto-incremented values for a table's PRIMARY KEY, starting at 1.

How does AUTO_INCREMENT work in MySQL?

MySQL AUTO_INCREMENT

Code example

MySQL `AUTO_INCREMENT`