Introduction to Database Management Systems (DBMS)
A Database Management System (DBMS) is software designed to manage databases. It provides an interface to create, retrieve, update, and delete data from a database, ensuring efficient data storage and retrieval. It handles the organization, storage, and retrieval of data in a systematic manner. Examples of DBMS include MySQL, Oracle, MS Access, and PostgreSQL.
In Class 12, the CBSE curriculum focuses on understanding the concepts, tools, and techniques used in database management, particularly using SQL (Structured Query Language).
Key Topics in Database Management (Class 12, CBSE)
- Database Concepts
- Database: A collection of related data that is stored in a structured way, usually in tables.
- DBMS: A software that manages the creation, maintenance, and manipulation of databases.
- Data: Raw facts and figures without context.
- Information: Processed data that is meaningful.
Types of DBMS
- Hierarchical DBMS: Data is stored in a tree-like structure (e.g., IBM’s IMS).
- Network DBMS: Data is represented using a graph structure (e.g., Integrated Data Store – IDS).
- Relational DBMS (RDBMS): Data is stored in tables and relationships are established between tables (e.g., MySQL, Oracle, MS SQL Server).
- Object-Oriented DBMS: Data is represented as objects, similar to how data is modeled in object-oriented programming.
Database Models
- Relational Model: Organizes data into tables (also called relations) with rows (tuples) and columns (attributes).
- Entity-Relationship Model (ER Model): Represents data using entities (objects) and relationships between them.
- Normalization: The process of organizing data to minimize redundancy and dependency by dividing large tables into smaller ones and linking them using foreign keys
SQL (Structured Query Language) SQL is the standard language used to interact with relational databases. In Class 12, students learn the following key SQL commands:
- DDL (Data Definition Language): Used to define the structure of the database.
CREATE: To create tables and databases.ALTER: To modify the structure of a database.DROP: To delete tables or databases.
- DML (Data Manipulation Language): Used to manage data within the database.
INSERT: To insert new records into a table.UPDATE: To modify existing records.DELETE: To remove records from a table.
- DCL (Data Control Language): Used to control access to data.
GRANT: To provide access privileges to users.REVOKE: To withdraw access privileges.
- TCL (Transaction Control Language): Deals with transaction management.
COMMIT: To save changes to the database.ROLLBACK: To undo changes made during the transaction.
- SELECT Query: Used to retrieve data from tables. Example:
SELECT column1, column2 FROM table_name WHERE condition;
Database Constraints Constraints are rules that define valid data in a database. Common constraints include:
- PRIMARY KEY: Uniquely identifies each record in a table.
- FOREIGN KEY: Establishes a relationship between two tables.
- NOT NULL: Ensures that a column cannot have a NULL value.
- UNIQUE: Ensures that all values in a column are unique.
- CHECK: Ensures that values in a column meet a specified condition.
Indexing Indexing is used to speed up the retrieval of records from a table. An index creates a data structure that allows for faster lookups of records.
Normalization Normalization is a process of organizing data in a database to reduce redundancy and improve data integrity. The process involves breaking down large tables into smaller, related tables and linking them using foreign keys. There are several normal forms (1NF, 2NF, 3NF) used to ensure that a database is normalize
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