1. Basic SQL Questions

1.1 What is SQL?

SQL (Structured Query Language) is a standard language used to interact with relational databases.

1.2 What are the different types of SQL commands?

SQL commands are categorized into:

• DDL (Data Definition Language): CREATE, ALTER, DROP, TRUNCATE
• DML (Data Manipulation Language): INSERT, UPDATE, DELETE
• DQL (Data Query Language): SELECT
• DCL (Data Control Language): GRANT, REVOKE
• TCL (Transaction Control Language): COMMIT, ROLLBACK, SAVEPOINT

1.3 What is the difference between SQL and MySQL?

• SQL is a language for managing databases.
• MySQL is a relational database management system (RDBMS) that uses SQL.

1.4 What are primary key and foreign key?

• Primary Key: A unique identifier for each row in a table. Cannot be NULL.
• Foreign Key: A column that references the primary key of another table to maintain relationships.

2. SQL Query Questions