"Relational Database Model"

Computer Science
Tutor: None Selected Time limit: 1 Day

  • Explain the key manner in which the business function / operation and the business rules associated with that business function / operation support the relationships mentioned above. Also, explain the fundamental ways in which the relationships could change, based on the interpretation of the given business rules.
Jul 5th, 2015

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Relational databases have been used by businesses for decades and they have steadily developed the features required for large-scale implementation, including scalability (in terms of user count and database size). The idea of relational databases was first suggested by Edgar Codd in 1969, and by the nineties, they had largely replaced hierarchical and network databases for business purposes. But the original definition is excruciatingly abstract, and no Codd-standard “true” relational database has ever been commercially released, although there are academic implementations.

Relational databases are now so widespread that it is hard to imagine a modern company without one. But it is not just the details of the relational model which give them such a firm position. The ubiquity of technical skills required to administer relational databases and a huge number of applications that use them guarantees that relational databases will be used for many years in the future. Another strength of relational databases is the widespread use of SQL, which makes it easy for an application to work with multiple relational databases. This was not true of hierarchical databases. Establishing SQL as a standard probably led to the development of the whole ERP industry and the rest of the OLTP applications market.

Please let me know if you need any clarification. I'm always happy to answer your questions.
Jul 5th, 2015

  • As explained throughout this course, entity relationship modeling is a critical element of database design. If the database is not properly modeled, it is unlikely that the database will be properly developed. Using this knowledge, explain the key reasons why entity relationship modeling is important, and determine at least (1) way in which it impacts the overall development of the database.

Jul 5th, 2015

Plain and simple, think of developing a database without an ERD as building a house without a building plan. It might be doable because you think that simply laying a brick one over another is enough to build something, however the moment somebody else takes responsibility over the project there is disaster potential.

In my experience you will not benefit much from ERDs unless you use them in conjunction with CASE tools (ERWin, MySQL Workbench etc.) which will additionally allow you to perform some really helpful operations such as forward and reverse engineering. Even without these functions having a centralized schematic of the complete database is useful because sometimes the constraints implemented in the database itself are not enough to tell the full story about the relationships between particular database entities.

Here is an example involving MySQL which, as you might know, implements several internal storage engines, most notably MyISAM and InnoDB. There are significant differences between them one of the most important one being that MyISAM doesn't support constraints. Despite that fact MyISAM is heavily used for web applications which means that the relational logic needs to be implemented either through business logic (application code) or in another way. The problem is when you forward engineer an ERD with MyISAM tables (entities) MySQL will silently ignore the constraints set by the ERD and you will end up with a database which doesn't clearly identify the nature of the relationships between entities. In other words after you develop the database layout there is no way for the code developers to implement proper business logic without an ERD.


Jul 5th, 2015

wow u are good

Jul 5th, 2015

  • Analyze the key ways that entity relationship modeling helps database developers overcome potential design challenges and conflicting goals.

Jul 5th, 2015

The result of the software requirements analysis (SRA) usually is a specification. The design helps us turning this specification into a working system. Hence software design includes architectural views, but also low-level component and algorithm implementation issues. Depending on the type, a software design may be platform-independent or platform-specific. There are many aspects to consider in the design of a piece of software. The importance of each should reflect the goals the software is trying to achieve.

Jul 5th, 2015

determine the major / minor challenges that might exist when you are creating an entity relationship diagram (ERD) for the business function / operation.

Jul 5th, 2015

A conceptual level entity relationship diagram (ERD) should be created to define the data needs of the customer and major business rules. The ERD needs to be able to 'talk to' the databases to tell them what to do.

Jul 5th, 2015

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