Databases and Database Systems - Essay Example

Database Databases and Database systems have become an essential component of everyday life in modern society. In the of a day, most of us encounter several activities that involve some interaction with a database. For example: banking operations, hotel and airlines reservation, a computerized library catalog to search or Internet vendor through its web page, all such activities involve someone or some computer program accessing a database. Real time and active database technology is used in controlling industrial and manufacturing and industrial processes and database search techniques are being applied to World Wide Web to improve the search for information that is needed by users browsing the Internet. A database management system is a collection of programs that enables user to create and maintain a database. In the Database Management System (DBMS), sharing a database allows multiple users and programs to access the database concurrently. Other important functions provided by the DBMS include protecting the database and maintaining it over a long period of time. Protection includes both system protections against hardware or software malfunction (or Crashes) and security protection against unauthorized or malicious access. A database typically has many uses, each of which may require a different perspective or view of the database. A multi user DBMS, as it name implies, must allow multiple users to access the database at the some time. This is essential if data for multiple applications to be integrated and maintained in a single database. The DBMS must include concurrency control software to ensure that several users trying to update the same data do so in a controlled manner so that the result of updates is correct. These types of applications are generally called online transaction processing applications. A fundamental role of multi users DBMS software is to ensure that concurrent transactions operate correctly. The concept of a transaction has become central to many database applications. A transaction is an executing program or process that includes one or more database accesses, such as reading or updating of database records. Each transaction is supposed to execute a logically correct database access if executed in its entirety without interference from other transaction. The DBMS must enforce several transaction properties. The isolation property ensures that each transaction appears to execute in isolation from other transactions, even though hundred of transaction may be executing concurrently. When multiple users share a large database, it is likely that most users with not be authorized to access all the information in the database. In addition some users may be permitted only to retrieve data where as others are allowed both to retrieve and update. Hence, the type of access operation must also be controlled. A DBMS should provide a security and authorization subsystem. As we know that, multiple users can access databases and use computer systems simultaneously because of the concept of multiprogramming. In this concurrent process, execution of processes is actually interleaved and most of the theory concerning concurrency control in database is developed in terms of interleaved concurrency. In a multi users DBMS, the stored data items are the primary resources that may be accessed concurrently by interactive users or application programs, which are constantly retrieving information and modifying the database. In this process, concurrency control is very mush needed to avoid certain type of problems. Concurrency control and recovery mechanisms are mainly concerned with the database access commands in transaction. Transaction submitted by the various users may execute concurrently and may access and update the same database items. If this concurrent execution is uncontrolled it may lead to problem such as inconsistent database, the lost update problem and temporary update problem. Transaction failure may occur due to integer overflow or division by zero or erroneous parameter values or logical programming errors (Elmasri et al., 2004). The concurrency control method will decides to abort the transactions, to be restarted later, because it violated serializability or because several transaction are in a state of deadlock. In the present circumstances, database security is a major concern especially in multi user and on -line users environment. Threats to databases result in the loss or degradation of some or all of the following security goals such as integrity, availability and confidentiality (Atluri et al., 1997). Database integrity refers to the requirement that information be protected from improper modification. In case of online or multi users environment, alternation of database, intentional and unauthorized is quite possible, which results in loss of system or data integrity and corrupt the data could result in inaccuracy, fraud or erroneous decisions. Similarly, database confidentiality has at most importance. The impact of unauthorized disclosure of confidential information can range from violation of data privacy, which can even jeopardize national security. Unauthorized, unanticipated or unintentional disclosure could result in loss of public confidence, embarrassment or legal action against the organization or person concerned. To protect databases against these types of threats four kinds of countermeasures can be implemented: access control, inference control, flow control and encryption. The security mechanism of a DBMS must include provisions for restricting access to database system as a whole. This function is called access control and is handled by creating user accounts and passwords to control the login process by the DBMS. Security for statistical database must ensure that information on individuals cannot be accessed. Prohibiting sequences of queries and partitioning the databases are the few techniques, which prevent database security and termed as inference control. Another security issue i. e. flow control, which prevents information from flowing in such a way that it reaches to unauthorized users. To prevent information flow through covert channels, one way to avoid, is for programmers to not actually gain access to sensitive data that a program is supposed to process. Covert channels are not a major problem in well-implemented robust database implementations. A final security issue is data encryption, which is used to protect sensitive data that is being transmitted via some type of communication network. Encryption can be used to provide additional protection for sensitive portions of the databases as well. The data is encoded using some coding provide additional protection for sensitive databases as well. The encryption techniques, including popular techniques such as public key encryption, which is heavily used to support Web-based transactions against databases, and digital signatures, which are used in personal communications. So security enforcements deal with controlling access to the databases system as a whole and controlling authorization to access specific portion of database (Stallings, 2000). The deluge of reports involving data the theft has brought to light a chilling fact: that confidential data were no longer safe with any agency. What's more shocking is that the data compromises were not the work of organized hackers. It was as ordinary as a careless employee storing customer information on a laptop that had got stolen, or banks is placing back-up tapes containing sensitive customer information while on transit. The revelations that have come back to back have shocked the country and the world community keenly watching the unfolding drama. The incidents have captured center-stage not because it does not happen, but because of the frequency and the magnitude of data compromise. These incidents question the very fundamentals of the networked world and point out some shocking truth. Meanwhile the months of headlines announcing the theft, misplacement or hacking of customer data has shaken the confidence of the public at large triggering a spate of legislation. Legislation can be expected to bring about some order to this chaos. But it would be too simplistic to think that itself would bring about changes in ensuring customer ID security. References: 1. Atluri, V., Jajodia, S., Keefe, T. F., McCollam, C., and Mukkamala, R. (1997) "Multilevel secure Transaction processing: Status and prospects," in Database security: Status and Prospects, Chapman and Hall, pp.79-98. 2. Elmasri, Ramez; Navathe, shamkant, B., (2004) Fundamentals of Database systems, 4th edn. Pearson Education Inc. 3. Stallings, W. (2000) Network Security essentials: Applications and Standards, Prentice Hall. Read More