Tutorial by Examples: w

Modal pages can created in three ways: From NavigationPage object for full screen pages For Alerts and Notifications For ActionSheets that are pop-ups menus Full screen modals ... // to open await Navigation.PushModalAsync(new ModalPage()); // to close await Navigation.PopModalAsync(); ...

SELECT Name FROM Customers WHERE PhoneNumber IS NULL Selection with nulls take a different syntax. Don't use =, use IS NULL or IS NOT NULL instead.

Given this data User_IDCompletion_Date12016-07-2012016-07-2122016-07-2022016-07-2122016-07-22 ;with CTE as (SELECT *, ROW_NUMBER() OVER (PARTITION BY User_ID ORDER BY Completion_Date DESC) Row_Num FROM Data) SELECT * FORM CTE WHERE Row_Num <= n Us...

First of all you need to create a class which extends RecyclerView.ItemDecoration : public class SimpleBlueDivider extends RecyclerView.ItemDecoration { private Drawable mDivider; public SimpleBlueDivider(Context context) { mDivider = context.getResources().getDrawable(R.drawable.divider_b...

CREATE UNIQUE INDEX idx_license_id ON Person(DrivingLicenseID) WHERE DrivingLicenseID IS NOT NULL GO This schema allows for a 0..1 relationship - people can have zero or one driving licenses and each license can only belong to one person

A 2-tuple or a 3-tuple represent a group of related items. (Points in 2D space, RGB values of a color, etc.) A 1-tuple is not very useful since it could easily be replaced with a single int. A 0-tuple seems even more useless since it contains absolutely nothing. Yet it has properties that make it v...

We start off with $db, an instance of the PDO class. After executing a query we often want to determine the number of rows that have been affected by it. The rowCount() method of the PDOStatement will work nicely: $query = $db->query("DELETE FROM table WHERE name = 'John'"); $count = ...

A true relational database must go beyond throwing data into a few tables and writing some SQL statements to pull that data out. At best a badly designed table structure will slow the execution of queries and could make it impossible for the database to function as intended. A database table shoul...

The core idea behind the Feature Branch Workflow is that all feature development should take place in a dedicated branch instead of the master branch. This encapsulation makes it easy for multiple developers to work on a particular feature without disturbing the main codebase. It also means the mast...

The Math.random() function should give random numbers that have a standard deviation approaching 0. When picking from a deck of card, or simulating a dice roll this is what we want. But in most situations this is unrealistic. In the real world the randomness tends to gather around an common normal...

Common Lisp REPL is an interactive environment. Every form written after the prompt is evaluated, and its value is afterwards printed as result of the evaluation. So the simplest possible “Hello, World!” program in Common Lisp is: CL-USER> "Hello, World!" "Hello, World!" CL...

You can create your own events and dispatch them, by extending the Event class. import flash.events.Event; class MyEvent extends Event { var data: String; static public var MY_EVENT_TYPE = "my_event_my_event_code"; public function MyEvent(type: String, data: Str...

Codename One is a set of tools for mobile application development that derive a great deal of its architecture from Java. Codename One's mission statement is: Unify the complex and fragmented task of mobile device programming into a single set of tools, APIs & services. As a result create a...

Template JS code Template.templateName.onCreated(function(){ this.subscribe('subsription1'); this.subscribe('subscription2'); }); Template HTML code <template name="templateName"> {{#if Template.subscriptionsReady }} //your actual view with data. it can ...

It's fairly common that you may create a class that implements IDisposable, and then derive classes that also contain managed resources. It is recommendeded to mark the Dispose method with the virtual keyword so that clients have the ability to cleanup any resources they may own. public class Paren...

This example wraps the asynchronous method oauth2.client.getToken(callback) from the package NPM package simple-oauth2into a Fiber so that the method may be called synchronously. const oauth2 = require('simple-oauth2')(credentials); const credentials = { clientID: '#####', clientSecret...

Customer[] customers = Customers.ToArray(); Purchase[] purchases = Purchases.ToArray(); var groupJoinQuery = from c in customers join p in purchases on c.ID equals p.CustomerID into custPurchases select new { CustName = c.Name, custPurchases }; ...

>>> import sys >>> a = object() >>> sys.getrefcount(a) 2 >>> b = a >>> sys.getrefcount(a) 3 >>> del b >>> sys.getrefcount(a) 2

Components in Vue are like widgets. They allow us to write reusable custom elements with desired behavior. They are nothing but objects which can contain any/all of the options that the root or any Vue instance can contain, including an HTML template to render. Components consist of: HTML marku...

String#replace can have a function as its second argument so you can provide a replacement based on some logic. "Some string Some".replace(/Some/g, (match, startIndex, wholeString) => { if(startIndex == 0){ return 'Start'; } else { return 'End'; } }); // will retur...