Tutorial by Examples: e

CASE's shorthand variant evaluates an expression (usually a column) against a series of values. This variant is a bit shorter, and saves repeating the evaluated expression over and over again. The ELSE clause can still be used, though: SELECT Id, ItemId, Price, CASE Price WHEN 5 THEN 'CHEAP' ...

When calling a function without an explicit namespace qualifier, the compiler can choose to call a function within a namespace if one of the parameter types to that function is also in that namespace. This is called "Argument Dependent Lookup", or ADL: namespace Test { int call(int i)...

void Main() { unsafe { int[] a = {1, 2, 3}; fixed(int* b = a) { Console.WriteLine(b[4]); } } } Running this code creates an array of length 3, but then tries to get the 5th item (index 4). On my machine, this printed 1910457872, bu...

Classes are identifiers for the elements that they are assigned to. Use the class attribute to assign a class to an element. <div class="example-class"></div> To assign multiple classes to an element, separate the class names with spaces. <div class="class1 class2&...

The ID attribute of an element is an identifier which must be unique in the whole document. Its purpose is to uniquely identify the element when linking (using an anchor), scripting, or styling (with CSS). <div id="example-id"></div> You should not have two elements with th...

To add an image to a page, use the image tag. Image tags (img) do not have closing tags. The two main attributes you give to the img tag are src, the image source and alt, which is alternative text describing the image. <img src="images/hello.png" alt="Hello World"> Yo...

You can apply any kind of additional processing to the output by passing a callable to ob_start(). <?php function clearAllWhiteSpace($buffer) { return str_replace(array("\n", "\t", ' '), '', $buffer); } ob_start('clearAllWhiteSpace'); ?> <h1>Lorem Ipsum&l...

Variables you have provided in your view context can be accessed using double-brace notation: In your views.py: class UserView(TemplateView): """ Supply the request user object to the template """ template_name = "user.html" def get_context_data...

The datetime module contains three primary types of objects - date, time, and datetime. import datetime # Date object today = datetime.date.today() new_year = datetime.date(2017, 01, 01) #datetime.date(2017, 1, 1) # Time object noon = datetime.time(12, 0, 0) #datetime.time(12, 0) # Curr...

C++11 for loops can be used to iterate over the elements of a iterator-based range, without using a numeric index or directly accessing the iterators: vector<float> v = {0.4f, 12.5f, 16.234f}; for(auto val: v) { std::cout << val << " "; } std::cout <<...

This uses the Dropbox Python SDK to upload a file to the Dropbox API from the local file as specified by file_path to the remote path as specified by dest_path. It also chooses whether or not to use an upload session based on the size of the file: f = open(file_path) file_size = os.path.getsize(fi...

foreach is used to iterate over the elements of an array or the items within a collection which implements IEnumerable✝. var lines = new string[] { "Hello world!", "How are you doing today?", "Goodbye" }; foreach (string line in lines) { Con...

Useful for simple animations, the CSS transition property allows number-based CSS properties to animate between states. Example .Example{ height: 100px; background: #fff; } .Example:hover{ height: 120px; background: #ff0000; } View Result By default, hovering over an...

When creating animations and other GPU-heavy actions, it's important to understand the will-change attribute. Both CSS keyframes and the transition property use GPU acceleration. Performance is increased by offloading calculations to the device's GPU. This is done by creating paint layers (parts of...

For multi-stage CSS animations, you can create CSS @keyframes. Keyframes allow you to define multiple animation points, called a keyframe, to define more complex animations. Basic Example In this example, we'll make a basic background animation that cycles between all colors. @keyframes rainbow...

Using Item Sales Table from Example Database, let us calculate and show the total Quantity we sold of each Product. This can be easily done with a group by, but lets assume we to 'rotate' our result table in a way that for each Product Id we have a column. SELECT [100], [145] FROM (SELECT ItemI...

In JavaScript, any object can be the prototype of another. When an object is created as a prototype of another, it will inherit all of its parent's properties. var proto = { foo: "foo", bar: () => this.foo }; var obj = Object.create(proto); console.log(obj.foo); console.log(obj....

Suppose we have a plain object called prototype: var prototype = { foo: 'foo', bar: function () { return this.foo; } }; Now we want another object called obj that inherits from prototype, which is the same as saying that prototype is the prototype of obj var obj = Object.create(prototype); N...

Setting a filter applies to all channels that you will subscribe to from that particular client. This client filter excludes messages that have this subscriber's UUID set at the sender's UUID: NSString *expression = [NSString stringWithFormat:@"(uuid != '%@'", se...

This example uses the Dropbox .NET library to try to get the metadata for an item at a particular path, and checks for a NotFound error: try { var metadata = await this.client.Files.GetMetadataAsync("/non-existant path"); Console.WriteLine(metadata.Name); } catch (Dropbox.Api.A...