UNIT II: BASICS OF SQL AND DATABASE DESIGN
1. SQL Fundamentals
SQL (Structured Query Language) is used for managing and manipulating relational databases. The
key components of SQL are:
a. SQL Data Types
Numeric: INT, FLOAT, DECIMAL
Character: CHAR, VARCHAR, TEXT
Date/Time: DATE, TIME, TIMESTAMP
Boolean: TRUE, FALSE
b. SQL Commands
DDL (Data Definition Language): CREATE, ALTER, DROP
DML (Data Manipulation Language): SELECT, INSERT, UPDATE, DELETE
DCL (Data Control Language): GRANT, REVOKE
TCL (Transaction Control Language): COMMIT, ROLLBACK, SAVEPOINT
c. Basic SQL Queries
SELECT column1, column2 FROM table_name WHERE condition;
INSERT INTO table_name (column1, column2) VALUES (value1, value2);
UPDATE table_name SET column1 = value WHERE condition;
DELETE FROM table_name WHERE condition;
2. Advanced SQL Features
a. Views
Views are virtual tables representing the result of a SQL query.
CREATE VIEW view_name AS
SELECT column1, column2 FROM table_name WHERE condition;
b. Indexing
Indexes speed up data retrieval operations.
CREATE INDEX index_name ON table_name(column_name);
c. Joins in SQL
INNER JOIN: Returns records with matching values in both tables.
