How to implement many-to-many relationships? What's the difference between a primary key and a unique key? What is user defined datatypes and when to use them? Define candidate key, alternate key, and composite key? Is there a column to which a default value can't be bound? What are ACID properties? Explain different isolation levels? What is MOLAP, ROLAP and HOLAP? Types of constraints? What are the types of indexes ? What are the type of the NonClustered Indexes ? In which situation NonClustered is more fast then clustered index? What is the difference between deadlock , live lock and blocking ? And How to resolve them? What are the Query Hints?