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JavaScript is a high-level scripting language used for implementing complex features on web pages. It allows developers to create dynamically updating content, control multimedia, animate images, and perform a wide range of other tasks. JavaScript runs in web browsers and is essential for many interactive web applications. Node.js is a cross-platform, open-source back-end JavaScript runtime environment. It enables developers to execute JavaScript code outside of a web browser, which makes it useful for writing command-line tools and server-side scripting. Node.js promotes a "JavaScript everywhere" paradigm, making it possible to use the same programming language for both client-side and server-side scripting. To write and run JavaScript code, you can use an online coding platform such as Replit. In JavaScript, variables are used to store and manipulate data. They can be declared using the var keyword, followed by the variable name and an optional initial value. Multiple varia...

  SQL Constraints, Primary key, Foreign key, SQL functions SQL Constraints SQL constraints are used to specify rules for the data in a table. Constraints are used to limit the type of data that can go into a table. This ensures the accuracy and reliability of the data in the table. It Prevents invalid data entry into the table. Constraints not null unique primary key foreign key check Note: check constraint will not be supported by MySQL. Note: some constraints we can apply at the column level and some constraints we can apply at the table level. Column Level: where we define the column not null unique primary key Table Level: after defining all the columns foreign key composite key (multi-column primary key) not null a null value is not allowed, that column will be mandatory. unique to that column duplicate values are not allowed. here we can insert null values multiple times. Note: whenever we define a unique constraint on a column then aut...

   Introduction, SQL basics: DDL, DML, DRL Java It is mainly used to develop a business application. Business Application Business organizations : the main objective for any business organization is profit. 1.  Small-scale business organizations (grocery shops, petrol pumps, they are running their services in a limited area.) 2.  Larger scale business organizations(Banks, railways, eCommerce, travel, insurance): these types of Business organizations are also called enterprises. These Business Organizations provide their services to the  client/customers,  and to  computerize those services  whatever application we develop is known as a  Business application. Common and general things in any business application: Storing and maintaining business data in a secure and easily retrievable manner. Processing the business data according to the business rules. Presenting the data to the user, in a user-understandable format. Note:  in real-time ...