1 INTRO TO DATABASES PART II IS 340 BY CHANDRA S. AMARAVADI

2 DBMS evolution file processing, hierarchical, relational ER Models Distributed databases Multi-media databases Data warehouses IN THIS PRESENTATION..

3 DBMS EVOLUTION

4 EVOLUTION OF DBMS File processing systems Hierarchical systems Relational systems 1 March 2002 Greece 2 July 2003 Italy 3 …………….. Person Photo1Photo2 GreeceItaly PhotoId

5 EVOLUTION OF DBMS.. FILE PROCESSING SYSTEMS:  Data in the form of “flat files” (ascii files)  Each program had its own specific files  Data was duplicated across files. A system where data was managed by the program in the form of flat files.

6 EVOLUTION OF DBMS.. PROBLEMS CAUSED BY FILE PROCESSING l Uncontrolled redundancy l Poor data quality (a.k.a.?) l Lack of data sharing

7 HIERARCHICAL MODEL l structure is hierarchical (not flat) l one or more root segments l child segments are linked hierarchically l difficult to write queries but very efficient (fast)! A model for storing data:

8 HIERARCHICAL MODEL NAMETOTAL_ENROLLNO_OF_PHD ASNAMEJOB_TITLEFNAMERANKDEGREE (D) DEPARTMENT (A) ADMIN-STAFF(F) FACULTY What do you call this?

9 Data organized into tables Data retrieved by using SQL, 4 th GL joins tables by equating values of cross reference keys. RELATIONAL MODEL 8895 Smith 4/16/00 $35, Farley 4/22/01 $ Gomez 1/10/00 $2,000 ACCT ACCT# NAME DT. OPENED BALANCE

10 ER MODELS (Data Models)

11 DEFINITIONS Entity – Individual example of person, place or thing. Entity Class – Collection of related entities. Attributes – Properties of entity classes about which we would like to collect information.

12 AN EXAMPLE ER CHART CUSTOMER ORDERS places Cust#Name PRODUCTS are for ENTITY CLASS ATTRIBUTE RELATIONSHIP Ord#Ord dt

13 Draw Data Models (ER models) corresponding to the following Situations: Athletes participate in events (qualifier, semi-finals, finals) in various sports (swimming, boxing etc.). Clients can book one or more properties with a rental agency. Each property can be booked by more than one client (for different dates). Trains arrive and depart from platforms in train stations, corresponding to the cities that they stop in. A city can have many Stations. Airlines operate a number of flights which arrive and depart from Gates. There could be several flights from a gate, but each flight is assigned only one gate. Each airline operates a gate or a set of Gates which are leased to them by the airport. DISCUSSION

14 Design a database for the following situation: Bellsouth, a telephone company needs a database to maintain records of its automobiles, repairs, mechanics and special equipment needed to repair cars. Mechanics are assigned skill codes based on the type of repairs they can carry out. For e.g. Class III mechanics can perform reborings, engine overhauls and transmission repairs. The repair shops are located in 300 cities and towns throughout the state. Mechanics can be assigned to only one repair shop at a time. The application requires knowing what equipment is (for e.g. diagnostic equipment, hydraulic machinery) is at what location and also the repairs carried out on each vehicle. For each vehicle the application requires knowing its identification number, mileage and repair history. DISCUSSION

15 DISTRIBUTED AND MULTI-MEDIA DATABASES, DATA WAREHOUSES

16 CENTRALIZED DATABASES u The database is in one physical location. u All applications regardless of whether the clients are located in Seoul or Detroit need to access data from that physical location. u What are the limitations? Centralized databases

17 DISTRIBUTED DATABASES u Replicated -- copies of the database maintained in multiple sites u Partitioned -- database is physically divided into chunks The data is physically stored in multiple geographical locations

18 REPLICATED DATABASES..

19 PARTITIONED DATABASES.. Emp IDEmp NameEmp Address 11049Richard200 Meadow brook 11051Cathy13 E. Willow 11054Hugh1400 E. Washington

20 MULTI-MEDIA DATABASES Emp IDEmp Name Emp. Picture Emp Address A database that is able to handle multiple data types: u Conventional information u Images u Audio & video Capable of storing, retrieving and updating this type of information Emp.jpg

21 MULTI-MEDIA DATABASES.. APPLICATIONS Travel bureaus Hospitals Manufacturing Training

22 MULTI-MEDIA DATABASES.. Storage space Retrieval Modification ISSUES

23 DATA WAREHOUSE: Historical data organized for analysis and decision making. DATA MART: smaller version of data warehouse, specialized by functional area e.g. marketing ON-LINE ANALYTICAL PROCESSING (OLAP): organizes data into a “cube” for decision analysis. DATA WAREHOUSES

24 HISTORICAL INFORMATION INTERNAL DATA SOURCES EXTERNAL DATA SOURCES OPERATIONAL, HISTORICAL DATA DATA WAREHOUSE EXTRACT, TRANSFORM OLAP DATA MINING DATA WAREHOUSING & OLAP

25 DISCUSSION QUESTIONS n Are Databases and DBMSs one and the same? n Does a record consist of files? n What is the smallest unit of data in the database? n Does data integrity refer to data quality? n What does the detail line of a report consist of? n Is an “employee” an entity class or an attribute? n Is the data dictionary useful while creating the database? n Why do we use SQL? n Is it necessary to use SQL to produce database reports? n Why do we use data models? n Would multi-national organizations prefer centralized databases?

26 THAT’S ALL FOLKS!