Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles by Ricky Barnes
Page 3 of 9
What is Zombie Process in Linux?
A zombie process is a process whose execution is completed but it still has an entry in the process table. Zombie processes usually occur for child processes, as the parent process still needs to read its child's exit status. Once this is done using the wait() system call, the zombie process is eliminated from the process table. This is known as reaping the zombie process. Zombie Process Life Cycle Parent Process Child Process ...
Read MoreHow to get the POST values from serializeArray in PHP?
The jQuery serializeArray() method serializes form elements into a JSON array of name-value pairs. When sent via $.post(), PHP receives these values through the $_REQUEST or $_POST superglobal. PHP Backend (serialize.php) This file receives and displays the POST values ? jQuery Frontend (HTML) The form collects user data and sends it using serializeArray() ? $(document).ready(function() { $("#driver").click(function(event) ...
Read MoreExtended Entity-Relationship (EE-R) Model
The Extended Entity-Relationship (EE-R) Model is a high-level data model that incorporates extensions to the original ER model to represent complex database requirements. In addition to basic ER concepts, EE-R includes − Subclasses and Super classes Specialization and Generalization Category or Union type Aggregation Subclasses and Super Class A super class contains common attributes shared by all its subtypes. Sub classes are groups of entities with unique attributes that inherit properties from the super class ? Shape ...
Read MoreForeign Key in RDBMS
A Foreign Key is a column (or set of columns) in one table that creates a link to the primary key of another table. It establishes a relationship between two tables and enforces referential integrity − ensuring that values in the foreign key column always correspond to valid values in the referenced primary key. Example Consider two tables − Employee and Department. The DeptID in the Employee table is a foreign key that references the DeptID primary key in the Department table ? Employee EmpID (PK) EmpName EmpAge DeptID (FK) 1 ...
Read MoreCandidate Key in RDBMS
A Candidate Key is a minimal set of attributes that can uniquely identify each row in a table. Each table may have one or more candidate keys, and one of them is chosen as the Primary Key. A candidate key is essentially a minimal super key − no attribute can be removed from it without losing uniqueness. Example 1: Employee Table In an Employee table, both EmployeeID and EmployeeEmail can uniquely identify each employee. Therefore both are candidate keys. You select any one of them as the primary key, since a table can have only a single primary ...
Read MoreSurrogate Key in RDBMS
A Surrogate Key is a system-generated unique identifier in a database that has no actual business meaning. Its only purpose is to uniquely identify each row in a table. Common examples include auto-increment integers, GUIDs, and system-generated codes. Surrogate Key vs Natural Key Unlike a natural key (like Student_ID or Email) which has real-world meaning, a surrogate key is purely artificial − it exists only to serve as a unique identifier for data management and analysis purposes. Example In the following ProductPrice table, the Key column is a surrogate key − it has no business meaning ...
Read MoreSuper Key in RDBMS
A Super Key is an attribute (or a set of attributes) that uniquely identifies a tuple (row) in a table. Any combination of columns that can uniquely identify each row is a super key. It is a superset of Candidate Key, since candidate keys are the minimal super keys with no redundant attributes. Example Consider the following Student table ? Student_ID Student_Enroll Student_Name Student_Email S02 4545 Dave ddd@gmail.com S34 4541 Jack jjj@gmail.com S22 4555 Mark mmm@gmail.com Super Keys The following are some of the super ...
Read MoreHow to add easing effect to your animation with jQuery?
To add easing effects to your jQuery animations, you need to use the animation speed properly and choose the right easing function to create perfect animations for your web page. The key is knowing when to speed up, slow down, and stop your animations while using the animate() method. jQuery provides several built-in easing options like "swing" and "linear", or you can use custom easing functions for more advanced effects. The "swing" easing creates animations that start slow, speed up, then slow down at the end, while "linear" maintains a constant speed throughout the animation. The key is to control ...
Read MoreHow to put a complete HTML page in a div using jQuery?
To put a complete HTML page in a div using jQuery, use the load() method. The load() method loads data from a server and puts the returned data into the selected element. This is particularly useful when you want to dynamically load content from another HTML file into a specific section of your current page. First, let's create the HTML page that you want to load. Here's the code for new.html − ...
Read MoreHow to get value from serialized array in jQuery?
To get value from serialized array, use the serializeArray() method. The serializeArray() method serializes all forms and form elements like the .serialize() method but returns a JSON data structure for you to work with. The serializeArray() method returns an array of objects containing name/value pairs, making it easy to access individual form field values. Each object in the array has two properties: name (the field name) and value (the field value). PHP Backend File Let's say we have the following PHP content in serialize.php file − Example The following example demonstrates ...
Read More