oracle, high security, stable performance, but the price is relatively more expensive than the other, generally used to do the security of the higher enterprise database, such as banks, telecommunications systems, etc.

ms-sql, Chinese interface, security is not as good as oracle, is a free database, so the service is certainly not as good as oracle, ms-sql Suitable for factory and mining enterprise database, beginners are easier to get started

db2 is IBM's database, not too much use, but also know these