Tutorial by Examples: st

A relation(or relation schema) in a given database is in first normal form, if the domain of all attributes of that relation is atomic. A domain is atomic if all the elements of that domain are considered to indivisible units. Suppose a relation employee, has attribute name, then the relation is not...

In the 32-bit world, the general-purpose registers fall into three general classes: the 16-bit general-purpose registers, the 32-bit extended general-purpose registers, and the 8-bit register halves. These three classes do not represent three entirely distinct sets of registers at all. The 16-bit...

Step 1. In your host machine (Windows/Linux/OSX), create an empty dir my_project. Step 2. Create a file named Vagrantfile with this: Vagrant.configure("2") do |config| config.vm.box = "gbarbieru/xenial" #An Ubuntu 16.04 based image config.vm.hostname = "my_project&...

a string (including GStrings) evaluates to true if not null and not empty, false if null or empty def s = '' ... if (s) println 's is not empty' else println 's is empty' will print: 's is empty'

my @data_array = (123, 456, 789, 'poi', 'uyt', "rew", "qas"); print Dumper @data_array; Using Data::Dumper gives an easy access to fetch list values. The Dumper returns the list values serialized in a way that looks like Perl code. Output: $VAR1 = 123; $VAR2 = 456; $VAR3 ...

You can get it either synchronously: var docId = Todos.insert({text: 'foo'}); console.log(docId); Or asynchronously: Todos.insert({text: 'foo'}, function(error, docId){ console.log(docId); });

It is possible to query an object about its instance variables using instance_variables, instance_variable_defined?, and instance_variable_get, and modify them using instance_variable_set and remove_instance_variable: class Foo attr_reader :bar def initialize @bar = 42 end end f = F...

Ruby offers define_method as a private method on modules and classes for defining new instance methods. However, the 'body' of the method must be a Proc or another existing method. One way to create a method from raw string data is to use eval to create a Proc from the code: xml = <<ENDXML ...

Oh-my-zsh is a community-driven framework for managing your zsh configuration. It contains many plugins, which extend functionality, themes, which manage the appearance of the shell and the prompt, and helpful functions that will make your terminal much more powerful and customizable. You can create...

Pre-requirements Check the requirements for each device type you wish to automate and make sure they're installed before attempting to use Appium! iOS Requirements Mac OS X 10.10 or higher, 10.11.1 recommended XCode >= 6.0, 7.1.1 recommended Apple Developer Tools (iPhone simulator SDK, com...

If you want to xcopy files with specific type to a new folder keeping the current folder structure you need only to do this xcopy [SourcePath]*.mp3 [DestinationPath] /sy

String Strings are created by wrapping the text with double quotes. Double-quoted strings can evalute variables and special characters. $myString = "Some basic text" $mySecondString = "String with a $variable" To use a double quote inside a string it needs to be escaped usi...

$hash = @{ city = 'Berlin' } $result = 'You should really visit {0}' -f $hash.city Write-Host $result #prints "You should really visit Berlin" Format strings can be used with the -f operator or the static [String]::Format(string format, args) .NET method.

Function Receive-TCPMessage { Param ( [Parameter(Mandatory=$true, Position=0)] [ValidateNotNullOrEmpty()] [int] $Port ) Process { Try { # Set up endpoint and start listening $endpoint = new-object System.Net.IPEndPoint(...

The Abstract Factory Pattern is a creational design pattern that can be used to define specific instances or classes without having to specify the exact object that is being created. function Car() { this.name = "Car"; this.wheels = 4; } function Truck() { this.name = "Truck"; ...

template <class InputIterator, class UnaryPredicate> InputIterator find_if (InputIterator first, InputIterator last, UnaryPredicate pred); Effects Finds the first element in a range for which the predicate function pred returns true. Parameters first => iterator pointing to the begin...

Detailed instructions on getting pyspark set up or installed.

Limit root (and any other SUPER-privileged user) to GRANT ... TO root@localhost ... That prevents access from other servers. You should hand out SUPER to very few people, and they should be aware of their responsibility. The application should not have SUPER. Limit application logins to the one...

The "host" can be either a host name or an IP address. Also, it can involve wild cards. GRANT SELECT ON db.* TO sam@'my.domain.com' IDENTIFIED BY 'foo'; Examples: Note: these usually need to be quoted localhost -- the same machine as mysqld 'my.domain.com' -- a specific domain; th...

Draw stars with flexible styling (size, colors, number-of-points). // Usage: drawStar(75,75,5,50,25,'mediumseagreen','gray',9); drawStar(150,200,8,50,25,'skyblue','gray',3); drawStar(225,75,16,50,20,'coral','transparent',0); drawStar(300,200,16,50,40,'gold','gray',3); // centerX, centerY: ...