XML, JSON, AND AJAX

XML is a language called eXtensible Markup Language. It's a way to format documents so that both humans and computers can read them easily. XML was made to help store and move data across the internet in a simple and flexible way. It uses tags to organize and structure data into nested elements. It's used in many areas, like web development and sharing information between different systems.

JSON, short for JavaScript Object Notation, is a simple way to exchange data. It's easy for both people and computers to understand. JSON is based on a part of the JavaScript programming language, making it familiar to developers who work with languages like C++, Java, and Python. It's a text format that can be used with many different programming languages, making it great for sharing data between systems.

AJAX, which stands for Asynchronous JavaScript and XML, is a method used in web development to update parts of a web page without needing to reload the entire page. It allows web applications to communicate with servers in the background, making the user experience smoother and more interactive. AJAX relies on a mix of JavaScript, XML (though JSON is often used instead nowadays), HTML, and CSS to achieve this dynamic behavior. It's a technique that enhances web applications by enabling them to fetch and send data without disrupting the user's browsing experience.

LEC: WHAT IS SQL

Structured Query Language is a language that manages data and handles structuring data especially in a relational database management system (RDBMS). It is used to communicate with and manipulate databases. It provides a versatile and powerful way to interact with data stored in tables which grants the users the ability to retrieve, insert, update, and delete data, as well as define and manage the structure of databases. 

Where do we see SQL?

SQL is deeply implemented in the blueprint of vast amounts of applications and websites across different kinds of industries. In the topic of E-commerce, SQL is used to manage databases extensively to handle product listings, inventory management, and order processing. In the topic of social media, platforms such as Facebook, Twitter, and LinkedIn utilizes SQL databases to manage user profiles, posts, comments, and interactions. From entertainment and media streaming services to library management systems and beyond, SQL serves as the backbone for storing, retrieving, and manipulating vast amounts of data that controls the digital experiences we interact with daily.

Fundamental Components and Operations of SQL 

SQL consists of several fundamental components and operations that enable users to interact with databases effectively. These include: 

Data Definition Language (DDL): 

DDL statements are used in order to create indices and define and manage relationships.

Data Manipulation Language (DML): 

DML statements are used to insert, update, and delete data stored in tables. 

LEC: EMBEDDED DATA MANIPULATION LANGUAGE

Embedded SQL in database management systems (DBMS) serves as a powerful tool for seamlessly integrating high-level programming languages with databases. It acts as a connector between applications and databases, facilitating data manipulation and communication. Embedded SQL is supported by various DBMS, allowing developers to choose the one that best fits their needs. 

The demand for embedded SQL arises from the desire to simplify database interactions for both application developers and end users. When users interact with an application, they often input values or submit requests that require accessing and modifying data in a database. By incorporating SQL queries directly into the application code, developers can perform these database tasks without burdening users with SQL complexities. 

The structure of embedded SQL begins with establishing a connection to the database. This is achieved using the CONNECT keyword, preceded by EXEC SQL to indicate that it is a SQL statement.

LEC: INTERACTIVE DATA MANIPULATION LANGUAGE

Interactive Data Manipulation Language (DML) in SQL refers to the subset of SQL commands that are used to interactively retrieve, manipulate, and manage the data stored within a database. Unlike Data Definition Language (DDL), which focuses on defining and modifying the structure of the database, DML is concerned with querying and modifying the data itself.

SELECT: It allows users to specify which columns to retrieve, filter rows based on specified criteria using the WHERE clause, and order the results using the ORDER BY clause. 

INSERT: is used to add new rows of data into a table. Users specify the table name and provide values for each column being inserted.

UPDATE: is used to modify existing data within a table. Users specify the table name, set new values for specific columns, and optionally specify a WHERE clause to filter which rows are updated. This command is useful for making changes to existing data in the database. 

DELETE: is used to remove rows of data from a table. Users specify the table name and optionally include a WHERE clause to specify which rows should be deleted. This command permanently removes data from the database, so caution is advised when using it. 

MERGE: combines the capabilities of INSERT, UPDATE, and DELETE into a single statement. It allows users to perform conditional insertions, updates, or deletions based on specified conditions, which can simplify complex data manipulation tasks.

LEC: DATA DEFINITION LANGUAGE

In SQL, the Data Definition Language (DDL) is a subset of SQL. It is used to define and manage the structure of a database in which it includes commands for creating, altering, and dropping database objects such as tables, views, indexes, and constraints. It defines the blueprint of a database and utilizes creation, modification, and management according to the desired structure.

CREATE: This command creates a new table with specified columns and data types using the CREATE TABLE statement. 

ALTER: This command enables modification of the structure of existing database objects. 

DROP: is used to remove existing database objects. Permanently deletes the specified objects and their associated data. 

TRUNCATE: is used to remove all records/rows from a table while keeping the table structure intact.

COMMENT: This command allows users to add comments or descriptions to the data dictionary. Comments can provide additional context or documentation for database objects, aiding in understanding and maintenance.