i agree with you shiva0077 even if ORACLE is soo expensive theres a lot of company which prefer to use ORACLE because its fast to retrieve the data when you do a querying.
I prefer MySQL because it's easier to use for small applications. Oracle has to be used in a very big organization/corporation. 10000+ users to make it viable.
it depends on what you need in developing a software but as for me the most demanded is SQL SERVER 2000/2005/2008. I've been using these databases for almost 5 years.
SQ L are used for small applications while oracle is the best database for large organization and can store more date with a great security and it is used for large applications.