Tutorial by Examples: e

Delete duplicate rows using CTE

Employees table : | ID | FirstName | LastName | Gender | Salary | +------+-----------+----------+--------+--------+ | 1 | Mark | Hastings | Male | 60000 | | 1 | Mark | Hastings | Male | 60000 | | 2 | Mary | Lambeth | Female | 30000 | | 2 | Mary | Lambe...

List of Comparison Operators

OperatorComparisonExample==Equali == 0===Equal Value and Typei === "5"!=Not Equali != 5!==Not Equal Value or Typei !== 5>Greater thani > 5<Less thani < 5>=Greater than or equali >= 5<=Less than or equali <= 5

Creating a Simple VB.NET WinForms Application using a Text Editor

Open a text editor (like Notepad), and type the code below: Imports System.ComponentModel Imports System.Drawing Imports System.Windows.Forms Namespace SampleApp Public Class MainForm : Inherits Form Private btnHello As Button ' The form's constructor: thi...

Benchmarking using microbenchmark

You can use the microbenchmark package to conduct "sub-millisecond accurate timing of expression evaluation". In this example we are comparing the speeds of six equivalent data.table expressions for updating elements in a group, based on a certain condition. More specifically: A data....

Overview of the basic path drawing commands: lines and curves

================== TODO: Link each of the drawing commands below to their individual examples. I don't know how to do this since the links to the individual examples point towards the "draft" folder. TODO: Add examples for these path "action" commands: stroke(), fill(), clip() ...

lineTo (a path command)

context.lineTo(endX, endY) Draws a line segment from the current pen location to coordinate [endX,endY] <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid red; } </style> <script> window.onload=(fun...

quadraticCurveTo (a path command)

context.quadraticCurveTo(controlX, controlY, endingX, endingY) Draws a quadratic curve starting at the current pen location to a given ending coordinate. Another given control coordinate determines the shape (curviness) of the curve. <!doctype html> <html> <head> <style...

bezierCurveTo (a path command)

context.bezierCurveTo(control1X, control1Y, control2X, control2Y, endingX, endingY) Draws a cubic Bezier curve starting at the current pen location to a given ending coordinate. Another 2 given control coordinates determine the shape (curviness) of the curve. <!doctype html> <html&gt...

rect (a path command)

context.rect(leftX, topY, width, height) Draws a rectangle given a top-left corner and a width & height. <!doctype html> <html> <head> <style> body{ background-color:white; } #canvas{border:1px solid red; } </style> <script> window.onload...

closePath (a path command)

context.closePath() Draws a line from the current pen location back to the beginning path coordinate. For example, if you draw 2 lines forming 2 legs of a triangle, closePath will "close" the triangle by drawing the third leg of the triangle from the 2nd leg's endpoint back to the firs...

beginPath (a path command)

context.beginPath() Begins assembling a new set of path commands and also discards any previously assembled path. It also moves the drawing "pen" to the top-left origin of the canvas (==coordinate[0,0]). Although optional, you should ALWAYS start a path with beginPath The discarding ...

With NetStatusEvent

package { import flash.events.NetStatusEvent; import flash.net.NetStream; import flash.net.NetConnection; import flash.events.Event; import flash.media.Video; import flash.display.Sprite; public class VideoWithNetStatus extends Sprite { private var video:V...

Elementary set operations

It's possible to perform elementary set operations with Matlab. Let's assume we have given two vectors or arrays A = randi([0 10],1,5); B = randi([-1 9], 1,5); and we want to find all elements which are in A and in B. For this we can use C = intersect(A,B); C will include all numbers which ...

Installation or Setup

Linux Requirements (r0.16.0) Mandatory As per current Apache-Pig documentation it supports only Unix & Windows operating systems. Hadoop 0.23.X, 1.X or 2.X Java 1.6 or Later versions installed and JAVA_HOME environment variable set to Java installation directory Optional Python 2.7 ...

Creating a Future

import scala.concurrent.Future import scala.concurrent.ExecutionContext.Implicits.global object FutureDivider { def divide(a: Int, b: Int): Future[Int] = Future { // Note that this is integer division. a / b } } Quite simply, the divide method creates a Future tha...

Consuming a Successful Future

The easiest way to consume a successful Future-- or rather, get the value inside the Future-- is to use the map method. Suppose some code calls the divide method of the FutureDivider object from the "Creating a Future" example. What would the code need to look like to get the quotient of...

Consuming a Failed Future

Sometimes the computation in a Future can create an exception, which will cause the Future to fail. In the "Creating a Future" example, what if the calling code passed 55 and 0 to the divide method? It'd throw an ArithmeticException after trying to divide by zero, of course. How would t...

Putting the Future Together

The previous examples demonstrated the individual features of a Future, handling success and failure cases. Usually, however, both features are handled much more tersely. Here's the example, written in a neater and more realistic way: object Calculator { def calculateAndReport(a: Int, b: Int...

Convert Exceptions into Either or Option Types

To convert exceptions into Either or Option types, you can use methods that provided in scala.util.control.Exception import scala.util.control.Exception._ val plain = "71a" val optionInt: Option[Int] = catching(classOf[java.lang.NumberFormatException]) opt { plain.toInt } val eitherI...

CROSS APPLY & LATERAL JOIN

A very interesting type of JOIN is the LATERAL JOIN (new in PostgreSQL 9.3+), which is also known as CROSS APPLY/OUTER APPLY in SQL-Server & Oracle. The basic idea is that a table-valued function (or inline subquery) gets applied for every row you join. This makes it possible to, for example...
SQL • JOIN

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