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Unformatted text preview: themselves to the database system in order to obtain
access to all or part of the data in the database.
3. Many database management systems support a program-level of security that
precludes unauthorized users from using particular programs that access the
Many database management systems support record-level security that
prevents unauthorized users from accessing or updating certain records, such as
employee records of top-level managers in an employee database.
Many database management systems even support field-level security that
prevents unauthorized users from accessing or updating sensitive information in
certain fields, such as salary.
6. Many database management systems support read-only access that prevents
unauthorized users from modifying certain information (they can only view the
7. All database management systems maintain a log of database accesses so that
in case of any security breach, the log records can be analyzed to detect the
possible cause of the problem.
Client-Server Database Systems With the proliferation of computer networks, it became possible to access the data
stored in a database from any system connected to the same network on which the
system having the database was located. This gave birth to the client-server model
of database systems. As shown in Figure 16.20, in this model the database is
stored at and managed by a computer system called the database server. It runs all
important modules of the database management system that deal with the
maintenance and processing of data (called server programs). On the other hand,
systems on the same network that are primarily meant for accessing data from the
database are called database clients. They serve as front-end systems to the
database and run those modules (called client programs) of the database
management system that facilitate specification of access requests. When a
database client needs some information from the database, it makes a request to
the database server. The request trav...
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- Spring '14