Though not good for replacing databases spreadsheets can be ideal tools for

Though not good for replacing databases spreadsheets

This preview shows page 51 - 54 out of 177 pages.

Though not good for replacing databases, spreadsheets can be ideal tools for analyzing the data storedin a database. A spreadsheet package can be connected to a specific table or query in a database and usedto create charts or perform analysis on that data.Structured Query LanguageOnce you have a database designed and loaded with data, how will you do something useful with it? Theprimary way to work with a relational database is to use Structured Query Language, SQL (pronounced“sequel,” or simply stated as S-Q-L). Almost all applications that work with databases (such as databasemanagement systems, discussed below) make use of SQL as a way to analyze and manipulate relationaldata. As its name implies, SQL is a language that can be used to work with a relational database. From a
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Ch.4: Data 45simple request for data to a complex update operation, SQL is a mainstay of programmers and databaseadministrators. To give you a taste of what SQL might look like, here are a couple of examples using ourStudent Clubs database.• The following query will retrieve a list of the first and last names of the club presidents:SELECT "First Name", "Last Name" FROM "Students" WHERE "Students.ID" =• The following query will create a list of the number of students in each club, listing the club nameand then the number of members:SELECT "Clubs.Club Name", COUNT("Memberships.Student ID") FROM "Clubs"An in-depth description of how SQL works is beyond the scope of this introductory text, but theseexamples should give you an idea of the power of using SQL to manipulate relational data. Many databasepackages, such as Microsoft Access, allow you to visually create the query you want to construct and thengenerate the SQL query for you.Other Types of DatabasesThe relational database model is the most used database model today. However, many other databasemodels exist that provide different strengths than the relational model. The hierarchical database model,popular in the 1960s and 1970s, connected data together in a hierarchy, allowing for a parent/childrelationship between data. The document-centric model allowed for a more unstructured data storage byplacing data into “documents” that could then be manipulated.Perhaps the most interesting new development is the concept of NoSQL (from the phrase “not onlySQL”). NoSQL arose from the need to solve the problem of large-scale databases spread over severalservers or even across the world. For a relational database to work properly, it is important that only oneperson be able to manipulate a piece of data at a time, a concept known as record-locking. But with today’slarge-scale databases (think Google and Amazon), this is just not possible. A NoSQL database can workwith data in a looser way, allowing for a more unstructured environment, communicating changes to thedata over time to all the servers that are part of the database.
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46 Information Systems for Business and BeyondDatabase Management SystemsScreen shot of the Open Office database management system
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