Tutorial by Examples: e

Pi The following returns the value of PI formatted to 6 decimal places. The actual value is good to DOUBLE; SELECT PI(); -> 3.141593

Angles are in Radians, not Degrees. All computations are done in IEEE 754 64-bit floating point. All floating point computations are subject to small errors, known as machine ε (epsilon) errors, so avoid trying to compare them for equality. There is no way to avoid these errors when using floating p...

Round a decimal number to an integer value For exact numeric values (e.g. DECIMAL): If the first decimal place of a number is 5 or higher, this function will round a number to the next integer away from zero. If that decimal place is 4 or lower, this function will round to the next integer value cl...

To raise a number x to a power y, use either the POW() or POWER() functions SELECT POW(2,2); => 4 SELECT POW(4,2); => 16

Use the SQRT() function. If the number is negative, NULL will be returned SELECT SQRT(16); -> 4 SELECT SQRT(-3); -> NULL

Generate a random number To generate a pseudorandom floating point number between 0 and 1, use the RAND() function Suppose you have the following query SELECT i, RAND() FROM t; This will return something like this iRAND()10.619143887068220.9384516830914230.83482678498591 Random Number in a r...

Return the absolute value of a number SELECT ABS(2); -> 2 SELECT ABS(-46); -> 46 The sign of a number compares it to 0. SignResultExample-1n < 0SELECT SIGN(42); -> 10n = 0SELECT SIGN(0); -> 01n > 0SELECT SIGN(-3); -> -1 SELECT SIGN(-423421); -> -1

Mixins are a sort of class that is used to "mix in" extra properties and methods into a class. This is usually fine because many times the mixin classes don't override each other's, or the base class' methods. But if you do override methods or properties in your mixins this can lead to une...

public class ConnectSocketExample { private int HTTP_PORT = 80; /** * example method to create unconnected socket * then connect to it * at end return connected socket * * @param httpHostName - endpoint host name fot socket connection * @throws IOEx...

/** * we reuse a class written in example: * http://stackoverflow.com/documentation/sockets/2876/introduction-to-sockets#t=201607262114505531351 * pleas to familiar with it first to continue with this one **/ public class WriteToSocketExample extends ConnectSocketExample { private ...

/** * Explain briefly what method does here * @param x Explain briefly what should be x and how this affects the method. * @param y Explain briefly what should be y and how this affects the method. * @return Explain what is returned from execution. */ def method(x: Int, y: String): O...

As ES6 introduced Symbols, which are both unique and immutable primitive values that may be used as the key of an Object property, instead of using strings as possible values for an enum, it's possible to use symbols. // Simple symbol const newSymbol = Symbol(); typeof newSymbol === 'symbol' // t...

5.1 This Example demonstrates how to automatically assign a value to each entry in an enum list. This will prevent two enums from having the same value by mistake. NOTE: Object.freeze browser support var testEnum = function() { // Initializes the enumerations var enumList = [ &q...

The SilverStripe CMS can be customised to change the CMS logo, link and application name. This can be achieved with the following config.yml settings LeftAndMain: application_name: 'My Application' application_link: 'http://www.example.com/' extra_requirements_css: - mysite/css/cms.c...

import java.util.Scanner; Scanner s = new Scanner(System.in); int number = s.nextInt(); If you want to read an int from the command line, just use this snippet. First of all, you have to create a Scanner object, that listens to System.in, which is by default the Command Line, when you start ...

SpriteKit functionality can be implemented in a subclass of SKScene. For example, a game may implement the main game functionality within an SKScene subclass called GameScene. In Swift: import SpriteKit class GameScene: SKScene { override func didMoveToView(view: SKView) { /* Co...

A simple use case it to create an SKScene that exactly fills the SKView. This avoids the need to consider scaling the view to fit or setting a camera to show a part of the scene. The following code assumes an SKView called skView already exists (e.g. as defined in Create a Full Screen SKView using ...

An SKScene has a scaleMode parameter that defines how it will change its size to fit within the SKView it is presented into the SKView if it is not the same size and/or shape. There are four options for scaleMode: AspectFit: the scene is scaled (but not stretched) until it fits within the view. ...

You can place an SKCameraNode into an SKScene to define which part of the scene is shown in the SKView. Think of the SKScene as a 2D world with a camera floating above it: the SKView will show what the camera 'sees'. E.g. the camera could be attached to the main character's sprite to follow the act...

Chaining assignments as part of a var declaration will create global variables unintentionally. For example: (function foo() { var a = b = 0; })() console.log('a: ' + a); console.log('b: ' + b); Will result in: Uncaught ReferenceError: a is not defined 'b: 0' In the above examp...