Representing complex relationship among data
A database may contain varieties of data interrelated to each other in numerous ways. A DBMS must have the capability to represent a variety of relationships between the data as well as to update and retrieve related data simply and efficiently.
Data is essential to any organisation and also confidential. In a shared system the multiple users share the data, all information has not been shared by all users. For instance, the salary of the employees has not been visible to anyone other than the department dealing in this. Therefore, database should be protected from unauthorised users. This is done by Database Administrator (DBA) by giving the usernames and passwords only to authorised users as well as granting privileges or the type of operation allowed. This is complete by using security and authorisation subsystem. Only authorised clients may use the database and their access types can be restricted to only retrieval, update, insert or delete or any of these. Let us take example; the Branch Manager of any company may have access to all data while the Sales Assistant may not have access to salary details.
Improved Backup and Recovery
A file-based system may fail to give measures to protect data from system failures. This lies only on the user by taking backups intermittently. DBMS gives facilities for recovering the hardware and software failures. A recovery and backup subsystem is liable for this. In case a program fails, it restores the database to a state in which it was before the implementation of the program.
Support for concurrent transactions
A transaction is defined as the unit of work. For illustration, a bank may be there in a transaction where an amount of Rs.5000/- is transmitted from account X to account Y. A DBMS also transmit multiple transactions to occur concurrently.