Oracle Interview questions

Total available count: 35
Subject - Databases
Subsubject - Oracle

What is a deadlock? Explain?

Two processes waiting to update the rows of a table, which are locked by other processes then deadlock arises. In a database environment, this will often happen because of not issuing the proper row lock commands. Poor design of front-end applications may cause this situation and the performance of the server will reduce drastically.

These locks will be released automatically when a rollback or commit operation performed or any one of these processes being killed externally. 

For example, Transaction A might hold a lock on some rows in the Accounts table and needs to update some rows in the Orders table to finish.

Next 5 interview question(s)

What is hash cluster?
Difference between an implicit & an explicit cursor.?
How you will avoid your query from using indexes?
When you use WHERE clause and when you use HAVING clause?
How will you delete duplicating rows from a base table?