Tutorial by Examples: i

SELECT item.item_id, uses.category, /* nonstandard */ COUNT(*) number_of_uses FROM item JOIN uses ON item.item_id, uses.item_id GROUP BY item.item_id will show the rows in a table called item, and show the count of related rows in a table called uses. It will also show the va...

#include <gtk/gtk.h>//jjk.c static void destroy(GtkWidget *widget, gpointer data) { gtk_main_quit(); } int main(int argc, char *argv[]) { gtk_init(&argc, &argv); GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL); gtk_window_set_title(GTK_WINDOW(window), "Window&quot...

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 = ...

To simplify your querying from ORACLE-DB, you may want to call your query like this: const oracle = require('./oracle.js'); const sql = "select 'test' as c1, 'oracle' as c2 from dual"; oracle.queryObject(sql, {}, {}) .then(function(result) { console.log(result.rows[0]['C...

If you just want to indicate the intent of an import (so you don't want to declare a global) but don't wish to bother with any explicit definitions, you can import an ambient module. // in a declarations file (like declarations.d.ts) declare module "jquery"; // note that there are no ...

trash is a minimalistic vendoring tool that you configure with vendor.conf file. This example is for trash itself: # package github.com/rancher/trash github.com/Sirupsen/logrus v0.10.0 github.com/urfave/cli v1.18.0 github.com/cloudfoundry-incubat...

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...

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...

NSMutableArray *array = [NSMutableArray arrayWithObjects:@"Ken", @"Tim", @"Chris", @"Steve",@"Charlie",@"Melissa", nil]; NSPredicate *bPredicate = [NSPredicate predicateWithFormat:@"SELF beginswith[c] 'c'"]; NSArray ...

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...

Location is a service that applications can use to interact with a browser's URL. Depending on which LocationStrategy is used, Location will either persist to the URL's path or the URL's hash segment. Location is responsible for normalizing the URL against the application's base href. import {Comp...

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. ...

Read the documentation in this order to easily learn postscript: Paul Bourke's excellent tutorial: http://paulbourke.net/dataformats/postscript/ Blue Book, first half, the original official tutorial: http://www-cdf.fnal.gov/offline/PostScript/BLUEBOOK.PDF Green Book, how to use posts...

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 Identity a = Identity a we have data Free Identity a = Pure a | Free (Identity (Free Identity a)) which is isomorphic to data Deferred a = Now a | Later (Deferred a) or equivalently (if you promise to evaluate the fst element first) (Nat, a), aka Writer...

Given data Maybe a = Just a | Nothing we have data Free Maybe a = Pure a | Free (Just (Free Maybe a)) | Free Nothing which is equivalent to data Hopes a = Confirmed a | Possible (Hopes a) | Failed or equivalently (if you promise to evalua...