1. Basic SQL Queries What is SQL? SQL (Structured Query Language) is a standard programming language for managing and manipulating relational databases. What are the different types of SQL commands? DDL (Data Definition Language): Commands like CREATE , ALTER , DROP . DML (Data Manipulation Language): Commands like SELECT , INSERT , UPDATE , DELETE . DCL (Data Control Language): Commands like GRANT , REVOKE . TCL (Transaction Control Language): Commands like COMMIT , ROLLBACK . What is a primary key? A primary key is a unique identifier for a record in a table. It cannot contain NULL values. What is a foreign key? A foreign key is a field in one table that uniquely identifies a row of another table. It establishes a relationship between the two tables. What is normalization? Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. What are the d...