DBMS

Introduction to SQL (Structured Query Language) SQL is the backbone of relational database management. It allows users to interact with and manipulate data stored in databases effectively. A Brief History of SQL Origin: SQL was developed in the 1970s by IBM during research on relational database technology. Name: It started as SEQUEL but was later renamed SQL (Structured Query Language) due to trademark reasons. What is SQL? SQL is a programming language designed to communicate with and manipulate databases. With SQL, users perform essential database tasks, commonly summarized as CRUD : C: Create R: Read U: Update D: Delete How Does SQL Help? SQL enables users to: Retrieve Data: Extract precise information using queries. Manipulate Data: Add, modify, or remove records in the database. Define Data: Create and modify the structure of databases (tables, views, indexes). Control Data: Manage who can access and alter the database by granting or revoking permissions. ...

What is Third Normal Form (3NF)? 3NF is a set of guidelines for organizing relational database tables to reduce data redundancy and improve data integrity. Achieving 3NF means your tables are well-structured and efficient. Here's what you need to know: The Two Main Rules for 3NF The table must already be in Second Normal Form (2NF). This means there are no partial dependencies; every non-key attribute is fully dependent on the whole primary key. There should be no transitive dependencies. A transitive dependency happens when a non-key column depends on another non-key column, not directly on the primary key. Transitive Dependency Example: If column A determines column B, and column B determines column C, then A indirectly determines C. In 3NF, we want to remove these indirect relationships unless the dependencies are on a candidate key. Example: Breaking Down a Table into 3NF Suppose we have a table: R (A, B, C) With the following dependencies: A → B B → C The Pr...