Tutorial by Examples: v

The following command imports CSV files into a MySQL table with the same columns while respecting CSV quoting and escaping rules. load data infile '/tmp/file.csv' into table my_table fields terminated by ',' optionally enclosed by '"' escaped by '"' lines terminated by '\n' ignore 1...

The option -v followed by an assignment of the form variable=value can be used to pass parameters to an awk program. This is illustrated by the punishment program below, whose job is to write count times the sentence “I shall not talk in class.” on standard output. The following example uses the v...

The awk language does not directly support variables local to functions. It is however easy emulate them by adding extra arguments to functions. It is traditional to prefix these variables by a _ to indicate that they are not actual parameters. We illustrate this technique with the definition of a...

// Returns the nth number in the Fibonacci sequence function fibonacci(n) { if (n === 1 || n === 0) { return 1; } else { return fibonacci(n - 1) + fibonacci(n - 2); } }

Custom events usually need custom event arguments containing information about the event. For example MouseEventArgs which is used by mouse events like MouseDown or MouseUp events, contains information about Location or Buttons which used to generate the event. When creating new events, to create a...

A cancelable event can be raised by a class when it is about to perform an action that can be canceled, such as the FormClosing event of a Form. To create such event: Create a new event arg deriving from CancelEventArgs and add additional properties for event data. Create an event using EventH...

Download and install Visual Studio Community 2015 Open Visual Studio Community Click File -> New -> Project Click Templates -> Visual C++ -> Win32 Console Application and then name the project MyFirstProgram. Click Ok Click Next in the following window. Check the Empty proj...

In many instances, you will want to send data from the R server to the JS client. Here is a very simple example: library(shiny) runApp( list( ui = fluidPage( tags$script( "Shiny.addCustomMessageHandler('message', function(params) { alert(params); });" ), ...

To set a value in NSUserDefaults, you can use the following functions: Swift < 3 setBool(_:forKey:) setFloat(_:forKey:) setInteger(_:forKey:) setObject(_:forKey:) setDouble(_:forKey:) setURL(_:forKey:) Swift 3 In Swift 3 the names of function is changed to set insted of set folloed by ...

To get a value in NSUserDefaults you can use the following functions: Swift arrayForKey(_:) boolForKey(_:) dataForKey(_:) dictionaryForKey(_:) floatForKey(_:) integerForKey(_:) objectForKey(_:) stringArrayForKey(_:) stringForKey(_:) doubleForKey(_:) URLForKey(_:) Objective-C -(nullab...

It is also possible to use variables as comments. This can be useful to conditionally prevent commands being executed: @echo off setlocal if /i "%~1"=="update" (set _skip=) Else (set _skip=REM) %_skip% copy update.dat %_skip% echo Update applied ... When using the ab...

Environment variables can be defined before the meteor call, like so: PORT=4000 meteor NODE_ENV="staging" meteor

Downloading a file from the internet is a very common task required by almost every application your likely to build. To accomplish this, you can use the "System.Net.WebClient" class. The simplest use of this, using the "using" pattern, is shown below: using (var webClient = n...

var A var is a reference variable, similar to variables in languages like Java. Different objects can be freely assigned to a var, so long as the given object has the same type that the var was declared with: scala> var x = 1 x: Int = 1 scala> x = 2 x: Int = 2 scala> x = "foo...

In javascript, assigning a non-primitive value (Such as Object, Array, Function, and many more), keeps a reference (an address in the memory) to the assigned value. Assigning a primitive value (String, Number, Boolean, or Symbol) to two different variables, and changing one, won't change both: var...

Be careful, this approach might be considered as a bad design for angular apps, since it requires programmers to remember both where functions are placed in the scope tree, and to be aware of scope inheritance. In many cases it would be preferred to inject a service (Angular practice - using scope ...

RewriteEngine on RewriteCond %{HTTP_REFERER} !^$ RewriteCond %{HTTP_REFERER} !^http://(www\.)?yourdomain.com/.*$ [NC] RewriteRule \.(gif|jpg|css)$ - [F] This blocks all the links to '.gif', '.jpg' and '.css' files which are not from the domain name http://www.yourdomain.com. Display alterna...

A powerful alternative to virtualenv is Anaconda - a cross-platform, pip-like package manager bundled with features for quickly making and removing virtual environments. After installing Anaconda, here are some commands to get started: Create an environment conda create --name <envname> pyth...

let numbers = [3, 1, 4, 1, 5] // non-functional for (index, element) in numbers.enumerate() { print(index, element) } // functional numbers.enumerate().map { (index, element) in print((index, element)) }

A HAVING clause filters the results of a GROUP BY expression. Note: The following examples are using the Library example database. Examples: Return all authors that wrote more than one book (live example). SELECT a.Id, a.Name, COUNT(*) BooksWritten FROM BooksAuthors ba INNER JOIN Aut...