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INTRO TO DATABASES Part I IS 340 BY CHANDRA S. AMARAVADI 1 IN THIS PRESENTATION.. Data vs information Database organization file, record, attribute/field DBMS activities and functions DBMS components Importance of databases 2 DATA VS INFORMATION 3 DEFINING DATA AND INFORMATION Data: Data consists of raw facts e.g. 298-2034 Information: Data presented in a context e.g. someone’s phone# Some more examples: a) IS340 a) IS340 is a core course for BBA. b) Joan Smith b) Joan Smith is an arts & sciences student c) Score was 94-72 c) Score in the Celtics-Bulls game was 94-72. 4 DATA IS NOT USUALLY ISOLATED Example information about a person Name: DOB: Profession: Address: Steve Nash 2-4-1965 Basket ball player 415 Walnut street. These describe a person more. They are called ????. 5 ANOTHER EXAMPLE Example information about a credit card transaction: Date: Time: Merchant: Card type: Issuer: 12/5/08 4:48 pm WIU Union Master Card First Bank These describe a transaction more. 6 ONE ATTRIBUTE HAS A UNIQUE VALUE One of these is always unique: Acct#: 4555950 Date: 12/5/08 Time: 4:48 pm Merchant: WIU Union Card type: Master Card Issuer: First Bank The unique attribute is called ??? 7 CHARACTERISTICS OF DATA/ INFORMATION WHAT CAN WE SAY ABOUT THE TWO TYPES OF DATA? Transaction#: Date: Time: Merchant: Card type: Issuer: 55643 12/5/08 4:08 pm WIU Union Master Card First Bank Transaction#: Date: Time: Merchant: Card type: Issuer: 55644 12/5/08 4:20 pm Vitales Master Card Midwest Bank 8 CHARACTERISTICS OF DATA/ INFORMATION… Transaction ID Transaction Date Transaction Time Merchant 55643 12/05/08 4:08 pm WIU Union 55644 12/05/08 4:20 pm Vitales Data is typically organized into ?? Transaction#: Date: Time: Merchant: Card type: Issuer: 55643 12/5/08 4:08 pm WIU Union Master Card First Bank 9 HISTORICAL APPROACH TO DATA 55643 55644 55644 55646 12/05/08 12/05/08 12/05/08 01/07/09 4:08pm 4:20pm 4:20pm 8:05am WIU Union Vitales Vitales Pizza Hut 55643 55644 55644 55646 $25.60 $38.00 $63.00 $55.00 Transaction ID Transaction Date Transaction Time Merchant 55643 12/05/08 4:08 pm WIU Union 55644 12/05/08 4:20 pm Vitales MasterCard Visa Visa American Express This is called ___________ __________. 10 FILE PROCESSING PROBLEMS What problems did the file processing approach result in? 11 DATABASE ORGANIZATION 12 DEFINITIONS Database - Organized collection of information DBMS - SW program to manage and provide controlled access to the data 13 DBMS ORGANIZATION Database – A group of related files File/table – A group of related records Record – a grouping of related fields Field – a grouping of characters (one row) Schema -- This is the logical view of the database (tables and fields) Primary key – An attribute whose values are unique within a file Database Files/tables Records Fields 14 DBMS ORGANIZATION Structure/schema Primary key Attributes/field names PROD# DESCR. PRICE QUANTITY Record IR888E Refrigerator $1,800 20 Record TS3233 Television $67 32 Attr. values 15 DBMS ACTIVITIES 16 DBMS ACTIVITIES & FUNCTIONS Activities with DBMS Define structure / schema Enter data modify data query data get reports 17 DBMS ACTIVITIES & FUNCTIONS Define structure/schema Field Name Data type Description Length Decimals Prod# Numeric Unique prod code 6 0 Descr Text Short prod description 25 0 Price Currency Product price 6 2 18 DBMS ACTIVITIES & FUNCTIONS Enter data -- Create a data entry form Heading PRODUCT DATA ENTRY Label Product #: Description: Data entry form Field 19 DBMS ACTIVITIES & FUNCTIONS Modify data Add Delete Records/field values Change 20 DBMS ACTIVITIES & FUNCTIONS Query data list products costing more than $2,000 Prod# Descr. Price > 2,000 Quantity Query by example form 21 RH PRODUCT LISTING Title PH Column Headings PRODUCT # DESCR. PRICE Detail Product # Descr. Price Fields PF Average Price RF Footer A report specification 22 GETTING DATA OUT.. PRODUCT LISTING PROD# M100 M150 DESCRIPTION Chair Table Average Price PRICE $ 50.00 $200.00 $153.00 A generated report 23 Activities with DBMS ◦ ◦ ◦ ◦ ◦ Define structure / schema Enter data modify data query data get reports DBMS components 24 Major Components of DBMS D B M S Kernel Data Defn. SQL Prog. Language Interface Data Dictionary Screen/ Report Gen. Appln. Gen. D B M S Kernel Export/Import DBMS COMPONENTS.. Data definition – the facility through which schema is defined. (how new tables are created). SQL interface – the facility through which SQL commands are typed in. Programming language interface – the facility which processes SQL commands embedded in application program. Also known as the host language interface. Data dictionary – the facility that records details about the schema, reports, data entry forms etc. Screen & reports- the facility through which data entry screens and reports are created. Appln. Generation- the facility through which applications are created. Export/Import -- the facility through which files can be imported/exported in different DBMS formats. DBMS Kernel -- the actual programs which interact with the O/S and carry out data I/O. USAGE OF DATA/INFORMATION Suppose we have detailed information on each and every transaction in a store, what can we do with that? What if a customer wants to return a shirt purchased in the store? What if a manager wants to know what products were sold on a particular day? 27 IMPORTANCE OF DBMS’s Databases are used: To store and record information e.g. bal, price, grades etc. To retrieve information e.g. check#432 cashed? To report information e.g. daily sales To answer queries e.g. how many shoes were sold? Advanced uses: To analyze trends Identify sales prospects 28 INTRO TO DATABASES - II IS 340 BY CHANDRA S. AMARAVADI 29 DBMS EVOLUTION 30 EVOLUTION OF DBMS File processing systems Hierarchical systems 1 March 2002 Greece 2 July 2003 Italy 3 …………….. Photo1 Greece Person Photo2 Italy Relational systems PhotoId 31 EVOLUTION OF DBMS.. FILE PROCESSING SYSTEMS: A system where data was managed by the program in the form of flat files. Data in the form of “flat files” (ascii files) Each program had its own specific files Data was duplicated across files. 32 EVOLUTION OF DBMS.. PROBLEMS CAUSED BY FILE PROCESSING Uncontrolled redundancy Poor data quality (a.k.a.?) Lack of data sharing 33 HIERARCHICAL MODEL.. Structure is hierarchical (not flat) There are one or more root segments segments are linked hierarchically Difficult to write queries but very efficient (fast)! 34 HIERARCHICAL MODEL (D) DEPARTMENT NAME (A) ADMIN-STAFF ASNAME JOB_TITLE TOTAL_ENROLL NO_OF_PHD (F) FACULTY FNAME RANK DEGREE What do you call this? 35 RELATIONAL MODEL Data organized into tables Data retrieved by using SQL, 4th GL joins tables by equating values of cross reference keys. ACCT ACCT# NAME DT. OPENED 8895 8896 8897 Smith Farley Gomez 4/16/90 4/22/91 1/10/00 BALANCE $35,000 $300 $2,000 36 THE DATABASE DEVELOPMENT APPROACH 37 Entity classes File 1 prod File 2 cust. empl. Organization Data base Data model 38 THE DATABASE CONCEPT.. Organizations need to collect and manage information. Typically this need can be summarized in terms of entity classes and their relationships Known as a (conceptual) data model/ER model ER model is converted to database model Implemented 39 Prog. 1 Prog. 2 Integrated conceptualization Convert it to design Go through development process DBMS Different Database users/programs can share the information easily Can access info via SQL Can get reports easily 40 GETTING INFORMATION FROM FILE PROCESSING CROSS REFERENCE REPORT CUSTOMER ACCTS. LOANS ACCT. DATA LOAN DATA 41 GETTING INFORMATION FROM A DATABASE ACCT ACCT# 8895 8896 8897 NAME Smith Farley Gomez DT. OPENED 4/16/90 4/22/91 1/10/00 BALANCE $35,000 $300 $2,000 How can We combine these two Tables? LOAN LID AMOUNT 9978 9978 9992 $6,000 $5,000 $1,000 INT. RATE BALANCE 6.0% 7.1% 8.5% $2,440 $5,000 $ 400 42 DATA MODELS 43 DATA MODELS -- BASIC CONCEPTS Data models: representations of relationships among entity classes Entity – Individual example of person, place or thing. Entity Class – Collection of related entities (eclass). Attributes – Properties of entity classes about which we would like to collect information. Primary key -- An attribute whose values are unique within an entity class (pkey). 44 DISCUSSION Classify the following as entity, entity class or attribute San Francisco Tires Customer Book ISBN# Neon Peoplesoft Cust. balance Microsoft Microsoft employees Date of Birth Invoice 45 DATA MODELS… Cardinality: Number of entities participating in a relationship A A A 1:1 1:M M:N B For each value of A, one and only one value of B and vice versa. B For each value of A, multiple values of B, but for each B only one A. B For each value of A, many values of B and vice versa. 46 DISCUSSION Identify the types of the following relationships company -- president instructor -- students plane -- pilots city -- convention centers department -- employees team -- players company -- city books – authors city -- subdivisions product -- warranty 47 AN EXAMPLE ER CHART Cust# Name ENTITY CLASS CUSTOMER ATTRIBUTE Places ORDERS Ord# Ord dt RELATIONSHIP Are for PRODUCTS 48 DISCUSSION Draw Data Models (ER models) corresponding to the following Situations: Students take courses from professors 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. 49 DISCUSSION 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. 50 DISTRIBUTED AND MULTI-MEDIA DATABASES, DATA WAREHOUSES 51 CENTRALIZED DATABASES Centralized databases The database is in one physical location. All applications regardless of whether the clients are located in Seoul or Detroit need to access data from that physical location. What are the limitations? 52 DISTRIBUTED DATABASES The data is physically stored in multiple geographical locations Replicated -- copies of the database maintained in multiple sites Partitioned -- database is physically divided into chunks 53 REPLICATED DATABASES.. 54 PARTITIONED DATABASES.. Emp Address Emp ID Emp Name 11049 11051 11054 Cathy Richard Hugh 200 Meadowbrook 13 E. Willow 1400 E. Washington ……. …….. ………………….. 55 PARTITIONED DATABASES The database is divided into chunks. What is the logical way of doing this? Different chunks are placed in different locations. All the locations are connected. What are the advantages and limitations? The database is in multiple physical locations 56 MULTI-MEDIA DATABASES A database that is able to handle multiple data types: Conventional information Images Audio & video Capable of storing, retrieving and updating this type of information Emp ID Emp Name Emp. Picture Emp Address Emp.jpg 57 MULTI-MEDIA DATABASES.. APPLICATIONS Travel bureaus Hospitals Manufacturing Training 58 MULTI-MEDIA DATABASES.. ISSUES Storage space Retrieval Modification 59 DATA WAREHOUSES 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. 60 DATA WAREHOUSING & OLAP OPERATIONAL, HISTORICAL DATA INTERNAL DATA SOURCES DATA WAREHOUSE EXTRACT, TRANSFORM HISTORICAL INFORMATION EXTERNAL DATA SOURCES 61 OLAP DATA MINING DISCUSSION QUESTIONS Are Databases and DBMSs one and the same? Does a record consist of files? What is the smallest unit of data in the database? Does data integrity refer to data quality? What does the detail line of a report consist of? Is an “employee” an entity class or an attribute? Is the data dictionary useful while creating the database? Why do we use SQL? Is it necessary to use SQL to produce database reports? If we have a number of diskettes in alphabetical sequence, is this an example of a file organization? If so, what type? Would multi-national organizations prefer centralized databases? 62 THAT’S ALL FOLKS! 63 THAT’S ALL FOLKS! 64 THAT’S ALL FOLKS! 65