Tutorial by Examples: b

Create Table mysql> CREATE TABLE account (acct_num INT, amount DECIMAL(10,2)); Query OK, 0 rows affected (0.03 sec) Create Trigger mysql> CREATE TRIGGER ins_sum BEFORE INSERT ON account -> FOR EACH ROW SET @sum = @sum + NEW.amount; Query OK, 0 rows affected (0.06 sec) The CRE...

Mongoid allows Embedded Associations: One-to-one: embeds_one / embedded_in One-to-many: embeds_many / embedded_in To add an association (lets say the User embeds_many addresses), add this to your User file: embeds_many :addresses and this to your Address model file: embedded_in :user ...

Mongoid tries to have similar syntax to ActiveRecord when it can. It supports these calls (and many more) User.first #Gets first user from the database User.count #Gets the count of all users from the database User.find(params[:id]) #Returns the user with the id found in params[:id] User.w...

#include <iostream> #include <functional> using std::placeholders::_1; // to be used in std::bind example int stdf_foobar (int x, std::function<int(int)> moo) { return x + moo(x); // std::function moo called } int foo (int x) { return 2+x; } int foo_2 (int x, in...

1) Create a Contract Class A contract class defines constants that help applications work with the content URIs, column names, intent actions, and other features of a content provider. Contract classes are not included automatically with a provider; the provider's developer has to define them and t...

globalize gem is a great solution to add translations to your ActiveRecord models. You can install it adding this to your Gemfile: gem 'globalize', '~> 5.0.0' If you're using Rails 5 you will also need to add activemodel-serializers-xml gem 'activemodel-serializers-xml' Model translations...

When an HTTP server receives a well-formed HTTP request, it must process the information that request contains and return a response to the client. A simple HTTP 1.1 response, may look like any of the following, usually followed by a number of header fields, and possibly a response body: HTTP/1.1 2...

As with request bodies, HTTP responses may contain a message body. This provides additional data that the client will process. Notably, 200 OK responses to a well-formed GET request should always provide a message body containing the requested data. (If there is none, 204 No Content is a more approp...

DELETE FROM `myTable` WHERE `someColumn` = 'something' The WHERE clause is optional but without it all rows are deleted.

A web worker is a simple way to run scripts in background threads as the worker thread can perform tasks (including I/O tasks using xmlHttpRequest) without interfering with the user interface. Once created, a worker can send messages which can be different data types (except functions) to the JavaSc...

This is the easiest syntax to define a function: square(n) = n * n To call a function, use round brackets (without spaces in between): julia> square(10) 100 Functions are objects in Julia, and we can show them in the REPL as with any other objects: julia> square square (generic func...

Sometimes you will have a grid of subplots, and you want to have a single legend that describes all the lines for each of the subplots as in the following image. In order to do this, you will need to create a global legend for the figure instead of creating a legend at the axes level (which wil...

The following design pattern is categorized as a creational pattern. An abstract factory is used to provide an interface for creating families of related objects, without specifying concrete classes and can be used to hide platform specific classes. interface Tool { void use(); } interf...

pacman is a simple package manager for R. pacman allows a user to compactly load all desired packages, installing any which are missing (and their dependencies), with a single command, p_load. pacman does not require the user to type quotation marks around a package name. Basic usage is as follows:...

C++11 It's possible to write a generic function (for example min) which accepts various numerical types and arbitrary argument count by template meta-programming. This function declares a min for two arguments and recursively for more. template <typename T1, typename T2> auto min(const T1 &...

static void testNumericPromotion() { char char1 = 1, char2 = 2; short short1 = 1, short2 = 2; int int1 = 1, int2 = 2; float float1 = 1.0f, float2 = 2.0f; // char1 = char1 + char2; // Error: Cannot convert from int to char; // short1 = short1 + short2; // Err...

PowerShell remoting must first be enabled on the server to which you wish to remotely connect. Enable-PSRemoting -Force This command does the following: Runs the Set-WSManQuickConfig cmdlet, which performs the following tasks: Starts the WinRM service. Sets the startup type on the WinRM ser...

You can read an a binary file using this piece of code in all recent versions of Java: Java SE 1.4 File file = new File("path_to_the_file"); byte[] data = new byte[(int) file.length()]; DataInputStream stream = new DataInputStream(new FileInputStream(file)); stream.readFully(data); s...

This code compiles: Integer arg = null; int x = arg; But it will crash at runtime with a java.lang.NullPointerException on the second line. The problem is that a primitive int cannot have a null value. This is a minimalistic example, but in practice it often manifests in more sophisticated f...

At run time the following would display a list of url in your console and continue computation payload = [{url:..., title:...}, {url=..., title=...}] main = payload |> List.map .url -- only takes the url |> Debug.log " My list of URLs" -- pass the url...