1. CHAPTER 8: MANAGING DATA RESOURCES

2. File Organization Terms Field: group of characters that represent something Record: group of related fields File: group of related records Database: group of related files Entity: a person, place, thing, event Attribute: a piece of information about an entity

3. Entities, Attributes & Key Fields

4. Traditional File Processing Each functional area has specialized applications Each application requires an unique data file, that is often a subset of the master file PROBLEMS WITH TRADITIONAL FILE PROCESSING Data integrity Data redundancy and confusion Program-data dependence Lack of flexibility Poor security Lack of data sharing and availability

5. The Database Approach Database –Collection of data organized to serve many applications efficiently –Data is centralized –Uses a database management system (DBMS) Software to create and maintain a database Allows individual business applications to extract and use the data they require

6. Logical and Physical Views Physical view –How data are organized and stored on physical media Logical View –How the data appear to an application programmer or end user –Could be multiple logical views DBMS allows logical and physical views to be separated

7. Three components of DBMS 1.Data definition language Defines each data element Used by programmers in creating database 2.Data manipulation language Used to manipulate data (e.g. SQL) 3.Data dictionary Stores and organizes information about the data

8. Types of Relations ONE-TO-ONE: STUDENT ID MANY-TO-MANY: STUDENT A STUDENT B STUDENT C CLASS 1 CLASS 2 ONE-TO-MANY: Department --> Faculty Member

9. Types of Databases Hierarchical DBMS –Older model –Treelike structure, one-to-many relationships Network DBMS –Also older model, allows many-to-many relationships Neither are as flexible nor as easy to use as relational DBMS

10. Relational DBMS Tables share a common data element

11. Basic Operations of Relational DBMS Select –Creates a subset of records that meet criteria –E.g. all records (rows) with part number = 137 Project –Creates a subset of columns –Allows user to create new tables, or views, of data Join –Allows user to combine tables –E.g. table of parts + supplier

12. Querying Databases: SQL SELECT –Lists the columns from tables that the user wants to see in the result FROM –Identifies the tables from which the columns will be selected WHERE –Includes conditions for selecting specific rows (records)

13. Designing Databases Entity-relationship diagram –A methodology for documenting databases –Illustrates relationships between entities –Relationship can be One-to-many One-to-one Many-to-many

14. Normalization Eliminates redundant data and awkward relationships Unnormalized relation for ORDER Normalized relation for ORDER

15. Distributed Databases A database can be stored at more than one location Parts or copies are physically stored in different locations

16. Management Requirements Data Administration Data Planning and Modeling DataBase Administration

17. Data Warehouses & Datamining Extracts current & historical data from operational systems Combined with external data Create database for analysis by management Usually read only

18. Databases and the Web