Both primary key and unique enforce uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where are unique creates a non-clustered index by default. Another major difference is that, primary key doesn’t allow NULLs, but unique key allows one NULL only.
- General Questions
- Technical Questions
- Project Management Questions
- Job Interview Puzzles
- Interview Advice
- Can you tell me what is Isolation Level?
- What is SQL state database?
- Explain Dynamic CSS?
- Explain the directory structure of a web application.
- Please explain the Vector class?
- What is the difference between Container-Managed Persistent (CMP) bean and Bean-Managed Persistent(BMP) ?
- What bug tracking system did you use?