Why most of the companies use oracle as backend

pros. High performance, high availablity, good community(metalik), gurus that spreed the oracle knowledge(tom, check the site of asktom.oracle.com), platform independent, stable for enterpprise features as other databases only have these features added in the latest version(such as partition, sql server old version didn't support it) cons. complex, expensive, and not easy to get a OCP certificate (if this is also a cons) which is not because it is difficult to pass but because you must join a training from oracle which is very expensive

if you want to know more about oracle then I refer you to go and visit its website www.oracle.com , I hope you will be able to clear your confusion regarding this superb platform. Have a nice day.

Oracle is a database management tool, n its quite good.Thats why companies use it. ur confusion to take it ? i didnt get, do u mean to study oracle or to take a job in oracle. In any case go ahead n pick it, even if new things come the knowledge of the existing ones will only be of help n u will be preferred. But a caution if u r intersted in core computer science n all, better dont go into any databasing stream, the job is monotonous . hope this clarfies ur doubt, else u can comment back.

One vantage: Great performance to data in big quantity. One disadvantage: Oracle don´t let you do for example two operations in the same time...