One Commit at a Time ! Series - 6

JAVA

class Lamp {

  // stores the value for light
  // true if light is on
  // false if light is off
  boolean isOn;

  // method to turn on the light
  void turnOn() {
    isOn = true;
    System.out.println("Light on? " + isOn);

  }

  // method to turnoff the light
  void turnOff() {
    isOn = false;
    System.out.println("Light on? " + isOn);
  }
}

public class Main {
  public static void main(String[] args) {

    // create objects led and halogen
    Lamp led = new Lamp();
    Lamp halogen = new Lamp();

    // turn on the light by
    // calling method turnOn()
    led.turnOn();

    // turn off the light by
    // calling method turnOff()
    halogen.turnOff();
  }
}

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SQL

SELECT - extracts data from a database
UPDATE - updates data in a database
DELETE - deletes data from a database
INSERT INTO - inserts new data into a database
CREATE DATABASE - creates a new database
ALTER DATABASE - modifies a database
CREATE TABLE - creates a new table
ALTER TABLE - modifies a table
DROP TABLE - deletes a table
CREATE INDEX - creates an index (search key)
DROP INDEX - deletes an index

The most commonly used SQL aggregate functions are:

MIN() - returns the smallest value of a column
MAX() - returns the largest value of a column
COUNT() - returns the number of rows in a set
SUM() - returns the sum of a numerical column
AVG() - returns the average value of a numerical column
Aggregate functions ignore null values (except for COUNT(*)).

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References :

https://www.programiz.com/java-programming/class-objects
https://www.w3schools.com/sql/sql_aggregate_functions.asp