Cognizant Software Developer interview questions

Interview Question 1 Tell at least two uses of NORMALIZATION in designing tables and other structures in a database ? Answer 1 Normalization ensures that a) there is no redundant data storage and b) data dependencies across tables (foreign keys) are suitable for the level of concurrency. Interview Question 2 How Databases handle concurrent SQL operations on same row of a table? Answer 2 Concurrent operations are handled by the use of "Locks". To be more clear, if one sql query is updating (INSERT/UPDATE) a particular row of a table, no other sql query would be able to update the same row at same point in time. However other sql queries can read (SELECT) columns from the row under updation. Interview Question 3 What is the simple difference between stack and queue type data structures? Answer 3 Stack operates in a Last In First Out (LIFO) fashion while Queue operates in a First In First Out fashion (FIFO). Interview Question 4 Can you tell real life examples for stack and queue ? Answer 4 Plates arranged one over the other in hotel is an example for stack. Plate that was placed last on top will be the first one to be removed from the stack. Queue in billing section of stores is an example for queue.