What is SQL, and how is it different from databases like MySQL or PostgreSQL? Explain the difference between WHERE and HAVING clauses with an example. What are Primary Key, Foreign Key, and Unique Key constraints? Difference between INNER JOIN, LEFT JOIN, and RIGHT JOIN? How does GROUP BY work, and why is it used with aggregate functions? What is Normalization, and why is it important in database design? Explain DDL, DML, and DCL commands with examples. What is an Index, and how does it improve query performance? Explain TRUNCATE, DELETE, and DROP differences in SQL. What are Views in SQL, and why are they useful?