Tutorial by Examples: d

Setting a field to NULL works exactly like with any other value: UPDATE Employees SET ManagerId = NULL WHERE Id = 4

For example inserting an employee with no phone number and no manager into the Employees example table: INSERT INTO Employees (Id, FName, LName, PhoneNumber, ManagerId, DepartmentId, Salary, HireDate) VALUES (5, 'Jane', 'Doe', NULL, NULL, 2, 800, '2016-07-22') ;

Use appearanceWhenContainedInInstancesOfClasses: to customize the appearance for instance of a class when contained within an instance of container class. For example customization of UILabel's textColor and backgroundColor within ViewController class will look like this: Set UILabel text color Sw...

Editing or updating a resource is a common purpose for APIs. Edits can be achieved by sending either POST, PUT or PATCH requests to the respective resource. Although POST is allowed to append data to a resource's existing representation it is recommended to use either PUT or PATCH as they convey a m...

Another common use of HTTP APIs is to delete an existing resource. This should usually be done using DELETE requests. If the deletion was successful, the server should return 200 OK; an appropriate error code if it was not. If our employee Charlie Smith has left the company and we now want to dele...

A cross-origin request must be sent including the Origin header. This indicates from where the request originated. For example, a cross-origin request from http://example.com to http://example.org would look like this: GET /cors HTTP/1.1 Host: example.org Origin: example.com The server will us...

The response to a CORS request must include an Access-Control-Allow-Origin header, which dictates what origins are allowed to use the CORS resource. This header can take one of three values: An origin. Doing this permits requests from that origin only. The character *. This permits requests from...

Allowing user credentials or the user's session to be sent with a CORS request allows the server to persist user data across CORS requests. This is useful if the server needs to check if the user is logged in before providing data (for example, only performing an action if a user is logged in - this...

When a server receives a preflight request, it must check if it supports the requested method and headers, and send back a response that indicates its ability to support the request, as well as any other permitted data (such as credentials). These are indicated in access-control Allow headers. The ...

var app = {}; app.signUp = function(){ app.userName = $('#userName').val(); app.password = $('#password').val(); app.email = $('#form-email').val(); app.phoneNumber = $('#form-phone').val(); app.emailRegex = ...

Mostly you will use "normal variables": set(VAR TRUE) set(VAR "main.cpp") set(VAR1 ${VAR2}) But CMake does also know global "cached variables" (persisted in CMakeCache.txt). And if normal and cached variables of the same name exist in the current scope, normal var...

To update CocoaPods by simply installing the gem again [sudo] gem install cocoapods Or for a pre-release version [sudo] gem install cocoapods --pre

The scope outside of any function or class is the global scope. When a PHP script includes another (using include or require) the scope remains the same. If a script is included outside of any function or class, it's global variables are included in the same global scope, but if a script is include...

A Regexp can be created in three different ways in Ruby. using slashes: / / using %r{} using Regex.new #The following forms are equivalent regexp_slash = /hello/ regexp_bracket = %r{hello} regexp_new = Regexp.new('hello') string_to_match = "hello world!" #All of th...

Same list level: - Cat - Dog - Goldfish Nested List: - - Cat - Dog - Goldfish

Static class properties that are defined with the public visibility are functionally the same as global variables. They can be accessed from anywhere the class is defined. class SomeClass { public static int $counter = 0; } // The static $counter variable can be read/written from anywhere...

let someValue : String = "Something the user entered" let text = NSMutableAttributedString(string: "The value is: ") text.appendAttributedString(NSAttributedString(string: someValue, attributes: [NSFontAttributeName:UIFont.boldSystemFontOfSize(UIFont.systemFontSize())])) ...

Equals is declared in the Object class itself. public virtual bool Equals(Object obj); By default, Equals has the following behavior: If the instance is a reference type, then Equals will return true only if the references are the same. If the instance is a value type, then Equals will...

Like any other java program, every swing program starts with a main method. The main method is initiated by the main thread. However, Swing components need to be created and updated on the event dispatch thread (or short: EDT). To illustrate the dynamic between the main thread and the EDT take a loo...

Modules have four associated keywords to make using them in other modules: alias, import, use, and require. alias will register a module under a different (usually shorter) name: defmodule MyModule do # Will make this module available as `CoolFunctions` alias MyOtherModule.CoolFunctions #...