Conditional and Repetitive Structures in JavaScript
Simple Conditional Structure
Not all problems can be solved using sequential structures. When a decision needs to be made, conditional structures are used. In our daily life, we face situations where we must decide. “Do I choose race A or race B?” “Should I wear these pants?” “Do I visit website A or website B?” “To go to work, do I choose path A or path B?” “When scheduling a race, do I choose the morning, afternoon, or evening shift?”
These problems often combine sequential and conditional structures.
Read MoreIntroduction to JavaScript Programming
JavaScript Introduction
JavaScript is a language for designing web pages. Its simplicity contributes to its widespread use. Unlike traditional programming languages like C, C++, or Delphi, JavaScript is a scripting or document-oriented language, similar to macro languages found in word processors and spreadsheets.
While primarily used for web development, you can execute JavaScript code outside a browser environment. As an interpreted language embedded within HTML, JavaScript instructions are analyzed
Read MoreSQL Queries and Relational Calculus: A Comprehensive Guide
(i) If A is an attribute of type integer in a table, then A*0 always evaluates
to 0 in SQL.
False (think of nulls)
(ii) Aliases (tuple variables) in SQL do not increase the power of the lan-
guage and are provided just for convenience. False
(iii) In SQL, all nested queries without correlated subqueries can be unnested. False
(iv) Nested queries in the from clause of SQL queries are provided just for
convenience and can always be eliminated. True
(v) SQL can express some queries that relational calculus
Database Management Systems: Architectures, Models, NoSQL, and Transactions
1) What is a Database? Explain the three-schema architecture with a neat diagram.
• A database is an organized collection of data stored in a computer system and usually controlled by a database management system (DBMS).
• The Three-Schema Architecture: The goal of the three-schema architecture is to separate user applications from the physical database.
1. The Internal Level (Internal Schema):
➢ Describes the physical storage structure of the database.
➢ Uses a physical data model and describes
Read MoreUnderstanding Database Transactions, ACID Properties, and Stored Procedures in SQL
Database Transactions
A database transaction is a sequence of one or more SQL operations treated as a single unit of work. It ensures that either all operations are completed successfully or none are applied, preserving data integrity.
ACID Properties of Transactions
Atomicity: Ensures that all operations within the transaction are completed successfully. If any operation fails, the entire transaction is rolled back.
Consistency: Ensures that the database moves from one valid state to another, maintaining
Read MoreDatabase Management Systems: Triggers, Views, Constraints, and Data Models
Triggers
A trigger is a block of code that automatically executes in response to specific events on a particular table or view in a database. They are stored in the database and invoked repeatedly when the defined conditions are met. Triggers are associated with events like:
- Data Definition Language (DDL) statements (CREATE, DROP, ALTER)
- Data Manipulation Language (DML) statements (UPDATE, INSERT, DELETE)
- Database operations (Startup, Shutdown, Login, Logout)
Trigger Syntax
CREATE OR REPLACE TRIGGER Trigger_