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Databases

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Databases

  1. 1. Introduction  Database: an organized collection of data  Database management system (DBMS): group of programs to manage database  Manipulates database  Provides an interface between database and the user of the database and other application programs  Database administrator (DBA): skilled IS professional who directs all activities related to an organization’s database 2
  2. 2. Data and Information Collection of data Database software organized so Database software also called database you can access, allows you to management system retrieve, and (DBMS) use it Create Create forms database and reports Add, Sort change, and and delete retrieve data data 3
  3. 3. The Database Approach  “Traditional” (ie-OLD) approach to database management: separate data files are created for each application  Results in data redundancy (duplication)  Data redundancy conflicts with data integrity  Database approach to database management: pool of related data is shared by multiple applications  Significant advantages over traditional approach 4
  4. 4. File Processing System Each Records in one department or file may not area within May have relate to organization weaknesses records in any has own set of other file files Isolated Data data—data redundancy— stored in same fields separate files stored in so it is multiple files difficult to access 5
  5. 5. Strengths of the database approach Reduced data Improved redundancy data integrity Shared data Easier access Reduced development time 6
  6. 6. The Hierarchy of Data  Field: typically a name, number, or combination of characters that describes an aspect of a business object or activity  Record: a collection of related data fields  File: a collection of related records  Database: a collection of integrated and related files Hierarchy of data: Fields records files databases 7
  7. 7. Relational Databases  MS-Access is an example of a relational database  Some terminology differences in relational databases:  Record equates to a Row  Field equates to a Column 8
  8. 8. File Keys  Key: field or set of fields in a record that is used to identify the record  Primary key: field or set of fields that uniquely identifies the record 9
  9. 9. Database Administration 1. Determine the purpose of the database 2. Design the tables 3. Design the records and fields  Design tables on paper first for each table  Each table should contain  Be sure every record has a unique data about one subject primary key  Use separate fields for logically distinct items  Do not create fields for information that can be derived from entries in 4. Determine the other fields relationships among  Allow enough space for each field the tables  Set default values for frequently entered data 10
  10. 10. Data Integrity Garbage in Degree to which data is correct Garbage in, garbage out (GIGO)—computer phrase Garbage out that means you cannot create correct information from incorrect data Data integrity is lost 11
  11. 11. Qualities of Valuable Information Accurate Verifiable Timely Organized Accessible Useful Cost-effective 12
  12. 12. Manipulating Data and Generating Reports  Query-By-Example (QBE): a visual approach to developing database queries or requests  Structured Query Language (SQL): standard query language for relational databases  Database programs can produce reports, documents, and other outputs 13
  13. 13. Step 1. Select the fields you want Queries to display in the resulting query. Request for specific data from a  database Query language consists of  simple, English-like statements that allow users to specify data to display, print, or store Step 2. Assign a name to the query, so you can open it later. Step 3. View query on the screen. 14
  14. 14. Structured Query Language (SQL)? Allows you to manage, update, and retrieve data • Has special keywords and rules included in SQL • statements SQL statement SQL statement results 15
  15. 15. Database Security Access privileges DBMS provides define activities means to ensure that specific user only authorized or group of users users can access can perform data Read-only privileges - Full-update privileges - user can user can view view and data, but change data cannot change it 16
  16. 16. Data Warehouse/Data Mining/Data Mart Data warehouse: database system that stores and manages data required to analyze historical and current transactions Quick and efficient Often uses a process called way to access large data mining to find patterns amounts of data and relationships among data Data mart is smaller Uses multidimensional version of data warehouse databases 17
  17. 17. Quote Alice came to a fork in the road. quot;Which road do I take?quot; she asked. quot;Where do you want to go?quot; responded the Cheshire cat. quot;I don't know,quot; Alice answered. quot;Then,quot; said the cat, quot;it doesn't matter.“ ~Lewis Carroll, Alice in Wonderland 18

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