Tutorial by Examples: c

A subquery in a FROM clause acts similarly to a temporary table that is generated during the execution of a query and lost afterwards. SELECT Managers.Id, Employees.Salary FROM ( SELECT Id FROM Employees WHERE ManagerId IS NULL ) AS Managers JOIN Employees ON Managers.Id = Employees.Id ...

SELECT Id, FName, LName, (SELECT COUNT(*) FROM Cars WHERE Cars.CustomerId = Customers.Id) AS NumberOfCars FROM Customers

package main import ( "fmt" "io/ioutil" ) func main() { files, err := ioutil.ReadDir(".") if err != nil { panic(err) } fmt.Println("Files and folders in the current directory:") for _, fileInfo := range fi...

To access member variables and member functions of an object of a class, the . operator is used: struct SomeStruct { int a; int b; void foo() {} }; SomeStruct var; // Accessing member variable a in var. std::cout << var.a << std::endl; // Assigning member variable b in v...

To create a pure JSON table you need to provide a single field with the type JSONB: CREATE TABLE mytable (data JSONB NOT NULL); You should also create a basic index: CREATE INDEX mytable_idx ON mytable USING gin (data jsonb_path_ops); At this point you can insert data in to the table and que...

Taking a complex JSON document in a table: CREATE TABLE mytable (data JSONB NOT NULL); CREATE INDEX mytable_idx ON mytable USING gin (data jsonb_path_ops); INSERT INTO mytable VALUES($$ { "name": "Alice", "emails": [ "[email protected]", ...

Creation of a Button is simple: Button sampleButton = new Button(); This will create a new Button without any text or graphic inside. If you want to create a Button with a text, simply use the constructor that takes a String as parameter (which sets the textProperty of the Button): Button samp...

The current stable version of scikit-learn requires: Python (>= 2.6 or >= 3.3), NumPy (>= 1.6.1), SciPy (>= 0.9). For most installation pip python package manager can install python and all of its dependencies: pip install scikit-learn However for linux systems it is recomm...

Returns unique values from an IEnumerable. Uniqueness is determined using the default equality comparer. int[] array = { 1, 2, 3, 4, 2, 5, 3, 1, 2 }; var distinct = array.Distinct(); // distinct = { 1, 2, 3, 4, 5 } To compare a custom data type, we need to implement the IEquatable<T> i...

Every case class defines an extractor that can be used to capture the members of the case class when pattern matching: case class Student(name: String, email: String) def matchStudent1(student: Student): String = student match { case Student(name, email) => s"$name has the following...

Strings in JavaScript can be enclosed in Single quotes 'hello', Double quotes "Hello" and (from ES2015, ES6) in Template Literals (backticks) `hello`. var hello = "Hello"; var world = 'world'; var helloW = `Hello World`; // ES2015 / ES6 Strings can be created...

If your string is enclosed (i.e.) in single quotes you need to escape the inner literal quote with backslash \ var text = 'L\'albero means tree in Italian'; console.log( text ); \\ "L'albero means tree in Italian" Same goes for double quotes: var text = "I feel \"high\&quot...

Swift textView.text = "Hello, world!" Objective-C: textView.text = @"Hello, world!";

Swift textView.textAlignment = .left Objective-C textView.textAlignment = NSTextAlignmentLeft;

Swift //System Font textView.font = UIFont.systemFont(ofSize: 12) //Font of your choosing textView.font = UIFont(name: "Font Name", size: 12) Objective-C //System Font textView.font = [UIFont systemFontOfSize:12]; //Font of your choosing textView.font = [UIFont fontWithName:...

Swift textView.textColor = UIColor.red Objective-C textView.textColor = [UIColor redColor];

To keep a container running in the background, supply the -d command line option during container startup: docker run -d busybox top The option -d runs the container in detached mode. It is also equivalent to -d=true. A container in detached mode cannot be removed automatically when it stops, t...

A Docker volume is a file or directory which persists beyond the lifetime of the container. It is possible to mount a host file or directory into a container as a volume (bypassing the UnionFS). Add a volume with the -v command line option: docker run -d -v "/data" awesome/app bootstrap....

fn to_test(output: bool) -> bool { output } #[cfg(test)] // The module is only compiled when testing. mod test { use super::to_test; // This function is a test function. It will be executed and // the test will succeed if the function exits cleanly. #[test] fn...

You have started an interactive rebase. In the editor where you pick your commits, you decide that something is going wrong (for example a commit is missing, or you chose the wrong rebase destination), and you want to abort the rebase. To do this, simply delete all commits and actions (i.e. all lin...