Tutorial by Topics: q

ActiveRecord is the M in MVC which is the layer of the system responsible for representing business data and logic. The technique that connects the rich objects of an application to tables in a relational database management system is Object Relational Mapper(ORM). ActiveRecord will perform queries...

The -- style of comment, which requires a trailing space, differs in behavior from the SQL standard, which does not require the space.

fetch(url, options)[.then(...)[.catch(...)]] The Fetch API is the most commonly used API for HTTP requests. It is modern, flexible and it uses promises. The XMLHttpRequest API is also used for HTTP requests and is mainly included so that developers may use their favorite existing librar...

Not everything in AngularJS has a KnockoutJS equivalent (for example ngCloack, or ngSrc). There are two main solutions typically available: Use the generic attr or event binding instead. Similar to custom directives in AngularJS, you can write your own custom binding handler if you need someth...

This about is taken directly from the JQuery Mobile website: http://jquerymobile.com/about/ "jQuery Mobile is a HTML5-based user interface system designed to make responsive web sites and apps that are accessible on all smartphone, tablet and desktop devices. It is built on the rock-solid j...

Linq queries are written using the Standard Query Operators (which are a set of extension methods that operates mainly on objects of type IEnumerable<T> and IQueryable<T>) or using Query Expressions (which at compile time, are converted to Standard Query Operator method calls). Query ...

Browser security prevents a web page from making AJAX requests to another domain. This restriction is called the same-origin policy, and prevents a malicious site from reading sensitive data from another site. However, sometimes you might want to let other sites make cross-origin requests to your ...

JSON_VALUE(expression , path) -- extract a scalar value from a JSON string. JSON_QUERY( expression [ , path ] ) -- Extracts an object or an array from a JSON string. OPENJSON( jsonExpression [ , path ] ) -- table-value function that parses JSON text and returns objects and properties in JSON as ...

PLSQL procedure is a group of SQL statements stored on the server for reuse. It increases the performance because the SQL statements do not have to be recompiled every time it is executed. Stored procedures are useful when same code is required by multiple applications. Having stored procedures eli...

Type qualifiers are the keywords which describe additional semantics about a type. They are an integral part of type signatures. They can appear both at the topmost level of a declaration (directly affecting the identifier) or at sub-levels (relevant to pointers only, affecting the pointed-to valu...

from django.contrib.postgres.fields import *RangeField IntegerRangeField(**options) BigIntegerRangeField(**options) FloatRangeField(**options) DateTimeRangeField(**options) DateRangeField(**options)

Queues allow your application to reserve bits of work that are time consuming to be handled by a background process.

Choosing between GET and POST GET requests, are best for providing data that's needed to render the page and may be used multiple times (search queries, data filters...). They are a part of the URL, meaning that they can be bookmarked and are often reused. POST requests on the other hand, are ...

FooModel.objects.filter(field_name__key_name='value to query')