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Need For DBMS


A secure system ensures that the data it contains is valid. Data integrity means that data is protected from deletion and corruption, both while it resides within the database, and while it is being transmitted over the network. Integrity has several aspects:

  • System and object privileges control access to application tables and system commands, so that only authorized users can change data.
  • Referential integrity is the ability to maintain valid relationships between values in the database, according to rules that have been defined.
  • A database must be protected against viruses designed to corrupt the data.
  • The network traffic must be protected from deletion, corruption, and eavesdropping.


A secure system makes data available to authorized users, without delay. Denial-of-service attacks are attempts to block authorized users’ ability to access and use the system when needed. System availability has a number of aspects:

Table 1-2 System Availability Aspects
Availability AspectDescription
ResistanceA secure system must be designed to fend off situations, or deliberate attacks, which might put it out of commission. For example, there must be facilities within the database to prohibit runaway queries. User profiles must be in place to define and limit the resources any given user may consume. In this way the system can be protected against users consuming too much memory or too many processes (whether maliciously or innocently), lest others be prevented from doing their work.
ScalabilitySystem performance must remain adequate regardless of the number of users or processes demanding service.
FlexibilityAdministrators must have adequate means of managing the user population. They might do this by using a directory, for example.
Ease of UseThe security implementation itself must not diminish the ability of valid users to get their work done.

Security Requirements in the Internet Environment

The Internet environment expands the realm of data security in several ways, as discussed in these sections: