Database Management. Technology Briefing. Modern organizations are said to be drowning in data but starving for information p.

Transcription

1 Technology Briefing Database Management Modern organizations are said to be drowning in data but starving for information p. 509 TB3-1

2 Learning Objectives TB3-2

3 Learning Objectives TB3-3

4 Database Management for Strategic Advantage Database technology is vital to an organization s success Variety of information collected and stored o Stock prices o Potential customers o Credit ratings of wholesalers o Etc. TB3-4

5 Database Management for Strategic Advantage (II) Database technology used for: o Gathering and storing customer information o Custom-tailoring catalogs and mailings o Fueling electronic commerce o Etc. TB3-5

6 Learning Objectives TB3-6

7 Database Foundations Then: o Card catalogs o File cabinets Now: o DBMS Create Store Organize Retrieve data o E.g., Microsoft Access TB3-7

8 Database Database o Collection of related data organized in a way to facilitate searches o Entities Something you collect data about E.g.: people, books TB3-8

9 Record Contains data about a single entity o Similar to catalog card TB3-9

10 Attributes Specific characteristic describing the entities o E.g.: name and social security number are attributes of a person TB3-10

11 Example: Entity Student Entity represented as a table, with rows as records and columns as attributes TB3-11

12 Advantages of the Database Approach 1. Program-data independence 2. Minimal data redundancy 3. Improved data consistency 4. Improved data sharing 5. Increased productivity of application development TB3-12

13 Advantages of the Database Approach (II) 6. Enforcement of standards 7. Improved data quality 8. Improved data accessibility 9. Reduced program maintenance TB3-13

14 Cost and Risks of the Database Approach 1. New, specialized personnel 2. Installation and management cost and complexity 3. Conversion costs 4. Need for explicit backup and recovery 5. Organizational conflict TB3-14

15 Effective Management of Databases Database Administrator (DBA) o Responsible for development and management of databases Works with system analysts and programmers Works with users and managers Implements security features Grants access rights o One of the key actors in creating a successful database TB3-15

16 Entering Data Forms o Enter data about a record o Field in a form corresponds to attribute in a record o Used to add, modify, or delete data TB3-16

17 Example: Computer-Based Form TB3-17

18 Querying Data Query: used to retrieve information Structured Query Language (SQL) o Example: Display students who earned an A o Writing SQL queries can become very complex TB3-18

19 Query by Example Simpler than SQL Drag-anddrop features Construct a sample of the data we would like to see TB3-19

20 Creating Database Reports Report o Compilation of data from the database Report generators o Retrieve, manipulate, and display data Example o Quarterly sales for a restaurant Adding Grouping TB3-20

21 Database Design Data need to be organized for retrieval and analysis o Key elements of a database Data Structure Data model o A map or a diagram representing entities and their relationships TB3-21

22 Example: Entities and Their Attributes TB3-22

23 Identifying Records Uniquely identifying records: o Primary Key Unique identifier E.g.: Student ID number, social security number o Combination primary key Combination of two or more attributes E.g.: identifying a student s grade for a particular class for a particular term Identifying records that share a common value o Secondary Key Attribute not used as a primary key E.g., Major TB3-23

24 Associations Used to relate information between tables Needed to retrieve information Example: Basketball league database TB3-24

25 Example: Basketball League Each table contains important data No way to learn which team plays in a specific stadium Need to make associations TB3-25

26 Example: Basketball League Foreign keys o Attributes used to link tables o Primary key in one table, foreign key in another o Need to create additional entity for many-to-many relationships TB3-26

27 Entity-Relationship Diagram Used to show associations between entities Important when designing complex databases o Entities: represented by boxes o Relationships: represented by lines Associations TB3-27

28 The Relational Model Primary DBMS approach (RDBMS) 3 dimensions o Entities represented as 2-dimensional tables Rows = records Columns = attributes o Tables joined based on common columns (3 rd dimension) Good design eliminates redundancy TB3-28

29 Data Redundancy Problematic if an attribute has to be changed o Need to change in multiple locations E.g., instructor s phone number TB3-29

30 Normalization Eliminate unnecessary redundancy o Create separate tables o Data only needs to be changed in a single location TB3-30

31 Data Dictionary Document that specifies what data needs to be entered o Attribute name o Key or not o Data type o Valid values Can be used to enforce business rules TB3-31

32 Linking Website Applications to Organizational Databases Users can access a variety of data via a company s web site o Web services help in integration of databases, regardless of physical location Need for adequate systems performance Get understanding of customer behavior TB3-32