Finals Question#1

Finals Question#1

For those who are working, interview your IT in-charge and ask him/her to describe the computer database systems used in the company. Write your answer in 1-2 paragraphs. Further, ask also the benefits and/or disadvantages derived from these database systems.

For those who are not working, research one company in the net who is using computerized database systems. Describe the use and/or nature of these systems and describe too the benefits/disadvantages from these systems. Include your reference.

Ans.

Database Management Systems (DBMS) are important. They underpin all the activities of a library management system by providing the basic storage and retrieval technology. The library application software sends data to and receives data from the DBMS which, if it is working properly, is hardly noticed at all. Yet great claims are made for different types of database and their particular offerings. You should at least be able to understand the basics to understand what you might be getting - or missing when you choose a Library Management System (LMS).

Network

							Network DBMS allowed complex data structures to be built but were inflexible and required careful design. Very efficient in storage and fast however - best examples are airline booking systems. Generally conform to the CODASYL standards. Example: IDMS from Cullinet. Note: Network DBMS describes the connections between data elements - not the ability to operate over a network. A pre-cursor to and largely superseded by Relational DBMS

Advantages:

• Fast
• Efficient
  

Disadvantages

• Inflexible
• Technically obsolete ( although many in commercial use)

Relational

								Arose from theoretical considerations of data structures in IBM by Dr Codd. True Relational DBMS use the Structured Query Language (SQL) to extract and update data and conform as closely as possible to the theoretical relational rules of normalisation. Oracle, Sybase, Informix etc are examples. Work best when the data structures have been "normalised" to eliminate data and field duplication. Data is organised within "Tables" (files) and relationships expressed between tables and data elements. Note that just because a system uses a Relational DBMS, it does not mean that the data structures have been properly defined in the first place. You can build rotten data structures with a good tool. See Data Structures. SQL is now the industry standard for data querying and updating of databases. Relational DBMS lend themselves very well to the library concepts of authority files. Advantages Overwhelmingly, the most popular type of DBMS in use and as a result technical development effort ensures that advances e.g. object orientation, web serving etc appear quickly and reliably. There are many, many third party tools such as report writers that are tuned to work with the popular Relational DBMS via standards such as Open Database Connectivity (ODBC). Offer distributed database and distributed processing options which might be advantageous for some large consortium libraries. Extremely well developed management tools and security with automatic data logging and recovery. Have Referential integrity controls ensure data consistency. Have Transactional integrity features to ensure that incomplete transactions do not occur. Disadvantages In the early days they were slow - Relational DBMS have to employ many tables to conform absolutely to the various normalisation rules. This can make them slow and resource hungry compared to more flexible (less rigorous?) systems. Most Relational DBMS do not now have performance problems. Some restrictions in field lengths. Field lengths are usually defined with a maximum. This can lead to occasional practical problems e.g. a publisher with a 300 character name - they are rare but it can happen! SQL does not provide an efficient way to browse alphabetically through an index. Thus some systems cannot provide a simple title A-Z browse.

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Mark Ian Menorias