Tutorial by Examples: p

Sometimes a query looks like this, with a * in the SELECT clause. SELECT item.*, /* nonstandard */ COUNT(*) number_of_uses FROM item JOIN uses ON item.item_id, uses.item_id GROUP BY item.item_id Such a query needs to be refactored to comply with the ONLY_FULL_GROUP_BY sta...

A typical use case for RxJS is creating HTTP requests and caching their results for some period of time. Also, we always want to run only one request at a time and share its response. For example the following code caches 1 item for max. 1000ms: var updateRequest = Observable.defer(() => makeMo...

Use may now use the connExecute-Function for executing a query. You have the option to get the query result as an object or array. The result ist printed to console.log. function connExecute(err, connection) { if (err) { console.error(err.message); return; } sql = ...

For more complicated projects, or in cases where you intend to gradually type a dependency, it may be cleaner to create a module. Using JQuery (although it does have typings available) as an example: // place in jquery.d.ts declare let $: any; export default $; And then in any file in your pr...

Use a <template> element to design a HTML template that you can then reuse in your code. <template id="Template1"> Hello, World ! <template> <div id="Target1"></div> <script> Target1.appendChild( Template1.content.cloneNode( tr...

Import an HTML file that will add a div with "Hello, World!" at the end of the main document's DOM tree. Imported file hello.html: <script> var div = document.createElement( 'div' ) div.innerHTML = 'Hello, World!' document.body.appendChild( div ) </script> Mai...

This example combines Custom Element, Template, Shadow DOM and HTML Import to display a the "Hello, World!" string in HTML. In file hello-world.html: <!-- 1. Define the template --> <template> Hello, World! </template> <script> var template = document....

In lua, the logical operators and and or returns one of the operands as the result instead of a boolean result. As a consequence, this mechanism can be exploited to emulate the behavior of the ternary operator despite lua not having a 'real' ternary operator in the language. Syntax condition and...

String and character literals provide an escape mechanism that allows express character codes that would otherwise not be allowed in the literal. An escape sequence consists of a backslash character (\) followed by one ore more other characters. The same sequences are valid in both character an st...

The async pipe subscribes to an Observable or Promise and returns the latest value it has emitted. When a new value is emitted, the async pipe marks the component to be checked for changes. When the component gets destroyed, the async pipe unsubscribes automatically to avoid potential memory leaks. ...

import React, { Component } from 'react'; import { Modal, Text, View, Button, StyleSheet, } from 'react-native'; const styles = StyleSheet.create({ mainContainer: { marginTop: 22, }, modalContainer: { marginTop: 22, }, }); class Example extends Component...

#import <Foundation/Foundation.h> int main() { NSLog(@"File :%s\n", __FILE__ ); NSLog(@"Date :%s\n", __DATE__ ); NSLog(@"Time :%s\n", __TIME__ ); NSLog(@"Line :%d\n", __LINE__ ); NSLog(@"ANSI :%d\n", __STDC__ ); ...

Given data Empty a we have data Free Empty a = Pure a -- the Free constructor is impossible! which is isomorphic to data Identity a = Identity a

Given data Empty a we have data Cofree Empty a -- = a :< ... not possible!

Given data Maybe a = Just a | Nothing we have data Cofree Maybe a = a :< Just (Cofree Maybe a) | a :< Nothing which is isomorphic to data NonEmpty a = NECons a (NonEmpty a) | NESingle a

Given data Either e a = Left e | Right a we have data Cofree (Either e) a = a :< Left e | a :< Right (Cofree (Either e) a) which is isomorphic to data Hospitable e a = Sorry_AllIHaveIsThis_Here'sWhy a e | EatThis a (Hospitable e a) or, if yo...

The appearance of the ScrollPane can be easily changed, by having some notions of "CSS" and respecting some control "properties" and of course having some "imagination". A) The elements that make up ScrollPane : B) CSS properties : .scroll-bar:vertical .track{} ...

The package clause is not directly binded with the file where it is found. It is possible to find common elements of the package clause in diferent files. For example, the package clauses bellow can be found in the file math1.scala and in the file math2.scala. File math1.scala package org { ...

Xcode have ability to run any script with hotkey. Here is example how to assign hotkey ⌘+⌥+⌃+⇧+T to open Terminal app in current project folder. Create bash script and save it in some folder #!/bin/bash # Project Name: $XcodeProject # Project Dir: $XcodeProjectPath # Workspace Dir: $X...

constexpr const size_t addressSize = sizeof(sockaddr_in); constexpr const uint16_t defaultPort = 80; // The port you want to use int serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); sockaddr_in serverAddress, clientAddress; memset(&serverAddress, 0, addressSize); serverAddress....