why do we need database management system

; in other words, a system that manages databases. Examples of DBMSes are
and. These are systems that can be used to manage transactional databases, such as HR systems, banking systems and so on. These are typically optimized for performing transactions. They are very good at returning discrete pieces of information, such as the current state of Mr.

Smith's bank account. A, on the other hand, is designed for totally different job. It is designed to give people information rather than data. An example of information would be that the profitability of our company has increased by 3% per month over the last six months. In order to provide good quality information for a company (in other words, in order to build a data warehouse) we have to overcome two main problems: The first: is the data is scattered across multiple transactional systems, so we have to extract it from those systems, transform it into a standardized format and finally load it into a central repository called a data warehouse.

The second is that we have to reorganize it so that it is presented to the users in an understandable way.

As a side issue we need to ensure that the information system is very responsive в in many cases we try to get response times down below two seconds. The term data warehouse, in its broadest sense, describes both the centralized repository and the system for delivering information в which is another way of saying that they are woefully sub-optimal for carrying out detailed and complex analysis.

First, we need the ability to have multiple users insert, update and delete data to the same data file without "stepping on each other's toes". This means that different users will not cause the data to become inconsistent, and no data should be inadvertently lost through these operations.

We also need to have a standard interface for data access, tools for data backup, data restore and recovery, and a way to handle other challenges such as the capability to work with huge volumes of data and users.