Custom «RelationalL Database Management System» Essay Paper Sample
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Most companies and departments used to manage the data in excel spreadsheet, using the Microsoft Excel. Data was manually entered into fields of excel spreadsheets. Data in excel spreadsheets was managed in format of columns and rows. Although, these worksheets worked well to manage the data on a small scale, but large companies and big departments needed more easily manageable database system. A Relational database management system (RDBMS) is a software program used to create, maintain, manipulate and modify the relational database. This is a simple collection of data into a table form, easy to access the relational data. Currently the RoboBoys excel sheets require to be managed in an easy and simple form, to reduce the burden for those, who enter the data manually in excel sheets.
Companies and departments use the databases to keep the track record of their various subjects, as they are significant to them. For example, a selling company keeps the track record of its products, stock, customers, departments, stores and salesmen etc. In all cases the tables in a database represents each subject. In concerned case the field of each subject falling in a table is identified as given in following figure 1.2. Before the identification of the fields, subjects are significantly identified and then each field is put into relevant table. In RoboBoys this name “RoboBoys” is the domain name of all subjects or tables. Each of subjects is added to table list. Initially, this list will contain limited number of subjects; it will grow when data base requirements are identified.
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Fig: 1.2 Fields with suggested objects or table A table contains one or more fields which are features or characteristics of table. Therefore a table is the basic foundation of a database. Table names in a database cover the subjects. In a given excel spreadsheet of RoboBoys the Customer List is a table with characteristic Customer name, address, City, State, Zip, Country, Phone, Email, Model, Color and Personalization. These characteristics are field names in a database. At this stage of database design suggested fields to relevant tables are finalized. It is easy to assign a field to a table. When subject of a table is known then field under that subject goes to table of that subject (Michael, 2003). Refine the structures of tables. Use paper to draw the tables avoiding the temptation of using the program of RDBMS.
It will be useful to explore further the concepts used in RDBMS in designing of a new database. These concepts are important to design a database. These concepts include as the tables discussed earlier, column & rows, relationships and keys (primary, foreign, simple, candidate and complex). A Spreadsheet in MS Excel consists of tables with rows and columns to form a simple database. While a RDBMS contains a number of tables which is virtually end point of database design. In RDBMS the word “Relation” is cornerstone in designing of a relational database. Tables are related to each other and share the common attributes. Data in a table is filled in its rows and columns.
A candidate key identifies a column or group of columns in a table. In a given table two rows do not have the same candidate key for columns or group of columns. The table has any number of candidate key. One of the candidate key is called as primary key and remaining keys are called as alternate keys. Primary key in case of table Product is given as
|Product Number||Name of product||Description||Colors||Notes|
|1234||Classic||3 feet high, standard||Red, Blue, Green||Can personalize up to 12 letters|
In other two tables of Build & ship schedule and Customer are Ship number and Customer number respectively.
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It is noted that a unique field always becomes primary key because other fields may have the similar properties. It can be explained by giving another example of table Book. A Book table may have the fields like Book name, authors name, price, ISBN and published year. In this case ISBN number will be the primary key because a book has unique ISBN number. This primary key is also used primarily to identify the rows in a table. A primary key is used to retrieve the data from table (Isrd Group, 2006). It can be called that there is one candidate key called as primary key. In case when there are more than one candidate keys then one of them become primary key and other alternate key. Candidate key is called as the primary key while alternate candidate key is called as secondary key. A Foreign key provides a link to another relation. By use of a foreign key, data from more than one table is navigated. A foreign key is created automatically when a relation between two tables is established. A relation between customer and product is made through foreign key, when a customer purchases a product from Product table.
In this paper concepts of Relational database management system are given to design a database. It is discussed that how the data is managed from Excel spreadsheets into a RDBMS. Important steps of relational database are given to refine the database. Relational concepts including the use of key are explained to avoid the conflicts after database has been designed. It is much focused to present the data of excel spreadsheet for the purpose of designing a new relational database.
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