WikiGalaxy
Introduction to RDBMS
What is RDBMS?
A Relational Database Management System (RDBMS) is a type of database management system that stores data in a structured format, using rows and columns. It enables users to create, update, and administer a relational database.
Core Features of RDBMS
RDBMS systems are characterized by their use of tables to store data, SQL for querying, and ACID properties to ensure transactions are processed reliably.
ACID Properties
ACID stands for Atomicity, Consistency, Isolation, and Durability. These properties guarantee that database transactions are processed reliably.
Benefits of Using RDBMS
RDBMS offers benefits such as data integrity, security, and ease of use, making it suitable for a wide range of applications.
Types of RDBMS
Hierarchical Database Model
This model organizes data in a tree-like structure, where each child node has only one parent node. It's suitable for applications with a clear hierarchical relationship.
Network Database Model
Similar to the hierarchical model, but allows more complex relationships with multiple parent nodes. It is more flexible in representing many-to-many relationships.
Relational Database Model
The most common model, which organizes data into tables (relations) that can be linked—or related—based on data common to each. It supports SQL queries for data manipulation.
Object-Oriented Database Model
Integrates object-oriented programming principles with database technology. Data is stored as objects, similar to how they are represented in object-oriented languages.
SQL and RDBMS
Structured Query Language (SQL)
SQL is the standard language used to communicate with RDBMS. It allows users to create, read, update, and delete data within the database.
SQL Commands
SQL is composed of various commands such as SELECT, INSERT, UPDATE, DELETE, which are used to perform different operations on the data.
Benefits of SQL
SQL provides a powerful, flexible, and efficient way to access and manipulate data, making it a critical tool for database management.
Normalization in RDBMS
What is Normalization?
Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. It involves dividing large tables into smaller, related tables.
Normal Forms
The normal forms are a series of guidelines to ensure that databases are free from certain types of anomalies. They include First Normal Form (1NF), Second Normal Form (2NF), and Third Normal Form (3NF).
Benefits of Normalization
Normalization helps in reducing data redundancy and inconsistency, making the database more efficient and easier to maintain.
Transactions in RDBMS
Understanding Transactions
A transaction in RDBMS is a sequence of operations performed as a single logical unit of work. It must be completed fully or not at all.
Importance of Transactions
Transactions ensure data integrity and consistency, even in the event of system failures. They help maintain the ACID properties.
Commit and Rollback
The COMMIT command saves all changes made during the transaction, while ROLLBACK undoes them, restoring the database to its previous state.
Indexes in RDBMS
What are Indexes?
Indexes are used to speed up the retrieval of data from a database table. They are created on columns that are frequently used in search conditions.
Types of Indexes
Common types of indexes include unique indexes, composite indexes, and full-text indexes, each serving different purposes and optimizing different types of queries.
Benefits of Indexes
Indexes significantly improve query performance by reducing the amount of data the database engine needs to scan to find the desired result.
Constraints in RDBMS
Defining Constraints
Constraints are rules applied to database columns to enforce data integrity. They ensure that the data adheres to certain criteria.
Types of Constraints
Common constraints include PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL, and CHECK, each serving a specific purpose in maintaining data accuracy.
Benefits of Constraints
Constraints help maintain the accuracy and reliability of the data within the database by preventing invalid data entry.
Joins in RDBMS
Understanding Joins
Joins are used in SQL to combine rows from two or more tables, based on a related column between them. They are essential for querying related data across multiple tables.
Types of Joins
Common types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN, each serving different scenarios for combining data.
Benefits of Joins
Joins enable complex queries that can retrieve comprehensive datasets from multiple tables, facilitating detailed data analysis.
