Database SQL Interview Questions

1. Write a SQL Query to find first day of month?
2. Why there is a performance difference between two similar queries that uses UNION and UNION ALL?
3. How to choose between a Clustered Index and a Non-Clustered Index?
4. How you can minimize deadlock situations in a database server?
5. When you should use low fill factor?
6. Explain First, Second, and Third database normalization form with examples?
7. What are the benefits of using stored procedures?
8. What is the difference between an explicit and an implicit lock
9. Discuss about lock granularity
10. Discuss the ACID properties for a transaction
11. How do TRUNCATE and DELETE work?
12. Contrast UNIQUE and PRIMARY KEY constraints
13. Do you know what log shipping is?
14. Talk about different kinds of joins and how does each work?
15. What does a NOLOCK hint do?
16. What is Index Fragmentation and how do you resolve it in SQL Server?
17. What is lock escalation in SQL Server and how does it affect blocking?
18. How can you resolve blocking problems caused by lock escalation in SQL Server? http://support.microsoft.com/kb/323630
19. What are the pros and cons of creating an index on a table?
20. What is the max length of an index key?