2. Introduction to Database

3. How to Organize Information?  What are the different structures we use to organize information?  What are the organizing principles?

4. Organizational Memory  Provides support for Transaction processing Transaction processing Decision making Decision making services Organizational memory Data Quality decisions Quality products Quality

5. Daily Interaction with Databases  Trip to a bank Processes conducted? Processes conducted? Withdraw, deposit, etc …Withdraw, deposit, etc … Stored data? Stored data? Customers, accounts, balances, employees, etc …Customers, accounts, balances, employees, etc …  Airline/Hotel reservation? Customer, airlines, airports, flights, times, captains, payment information Customer, airlines, airports, flights, times, captains, payment information  Book purchase from Amazon.com? Book inventory, customer, credit card, credit card company, Amazon’s balance, your balance, etc … Book inventory, customer, credit card, credit card company, Amazon’s balance, your balance, etc …

6. Data, Information, and Knowledge  Data Raw, unsummarized, and unanalyzed facts Raw, unsummarized, and unanalyzed facts  Information Data processed into a meaningful form Data processed into a meaningful form One person's information can be another's data One person's information can be another's data  Knowledge Knowing what information is required Knowing what information is required Knowing what the information means Knowing what the information means Data InformationConversion Decision Knowledge Interpretation Request

7. What is a Database? What is a Database?  A database is a collection of related data  Implicit properties: A database represents some aspect of real-world (miniworld) A database represents some aspect of real-world (miniworld) A database is designed for some specific application A database is designed for some specific application It has an intended group of users It has an intended group of users

8. What is a DBMS?  A database is a mechanized, shared, formally defined and centrally controlled collection of data.  Implications: 2 Multiple Independent Users 2 Concurrent Access 2 Central Repository 2 Information

9. Typical DBMS Functionality   Define a database in terms of data types, structures and constraints   Construct or load (with data) the database on a secondary storage medium   Manipulating the database: querying, generating reports, insertions, deletions and modifications to its content   Concurrent processing and sharing by a set of users and programs yet, keeping all data valid and consistent!   Other features (useful but not mandatory): Protection (against malfunction) or security measures to prevent unauthorized/malicious access

10. Database Users  End-users: interact with the database applications  Application programmers  Database administrator (DBA) Deciding information content of database Deciding information content of database Deciding storage structure and access strategy Deciding storage structure and access strategy Interact with users Interact with users Defining security and integrity checks Defining security and integrity checks Backup and recovery strategy Backup and recovery strategy Monitoring performance Monitoring performance

11. Files and Databases  File: A collection of records or documents dealing with one organization, person, area or subject. (Rowley) Manual (paper) files Manual (paper) files Computer files Computer files  Database: A collection of similar records with relationships between the records. (Rowley) bibliographic, statistical, business data, images, etc. bibliographic, statistical, business data, images, etc.

12. Traditional File Processing vs. Database Sales Order program Payroll program Employee CustomerInventorySalesman Invoicing program Customer Traditional File processing approach EmployeeCustomerInventory DBMS Other data Database as a collection of related files Sales Order programPayroll programInvoicing program

13. File Based Systems Naughty Nice Just what asked for Coal Estimation Delivery List Application File Toys Addresses Toys

14. Traditional File-Based Systems A collection of application programs that perform services for the end-users such as the production of reports. Each program defines and manages its own data. A collection of application programs that perform services for the end-users such as the production of reports. Each program defines and manages its own data.  Limitations of the File-Based Approach: Separation and isolation of data Separation and isolation of data Duplication of data Duplication of data Data dependence Data dependence Incompatible file format Incompatible file format Fixed queries Fixed queries

15. Disadvantages of File Processing  Program-Data Dependence All programs maintain metadata for each file they use All programs maintain metadata for each file they use  Duplication of Data Different systems/programs have separate copies of the same data Different systems/programs have separate copies of the same data  Limited Data Sharing No centralized control of data No centralized control of data  Lengthy Development Times Programmers must design their own file formats Programmers must design their own file formats  Excessive Program Maintenance 80% of of information systems budget 80% of of information systems budget

16. Problems with Data Dependency   Each application programmer must maintain their own data   Each application program needs to include code for the metadata of each file   Each application program must have its own processing routines for reading, inserting, updating and deleting data   Lack of coordination and central control   Non-standard file formats

17. Figure 1-2 Three file processing systems at Pine Valley Furniture Duplicate Data

18. Problems with Data Redundancy  Waste of space to have duplicate data  Causes more maintenance headaches  The biggest problem: When data changes in one file, could cause inconsistencies When data changes in one file, could cause inconsistencies Compromises data integrity Compromises data integrity

19. SOLUTION: The DATABASE Approach  Central repository of shared data  Data is managed by a controlling agent  Stored in a standardized, convenient form Requires a Database Management System (DBMS)

20. Database Management System DBMS manages data resources like an operating system manages hardware resources  A software system that is used to create, maintain, and provide controlled access to user databases

21. DBMS Benefits  Minimal Data Redundancy  Consistency of Data  Integration of Data  Sharing of Data  Ease of Application Development  Uniform Security, Privacy, and Integrity Controls  Data Accessibility and Responsiveness  Data Independence  Reduced Program Maintenance

22. Disadvantages  Complexity  Size  Cost of DBMS  Additional hardware costs  Cost of conversion  Performance  Higher impact on failure

23. Terms and Concepts  Data Independence Physical representation and location of data and the use of that data are separated Physical representation and location of data and the use of that data are separated The application doesn’t need to know how or where the database has stored the data, but just how to ask for it.The application doesn’t need to know how or where the database has stored the data, but just how to ask for it. Moving a database from one DBMS to another should not have a material effect on application programMoving a database from one DBMS to another should not have a material effect on application program Recoding, adding fields, etc. in the database should not affect applicationsRecoding, adding fields, etc. in the database should not affect applications

24. Types of Database Systems  PC Databases  Centralized Database  Client/Server Databases  Distributed Databases  Database Models

25. PC Databases E.G. Access FoxPro Dbase Etc.

26. Centralized Databases Central Computer

27. Client Server Databases Network Client Database Server

28. Distributed Databases computer Location A Location C Location B Homogeneous Databases

29. Distributed Databases Local Network Database Server Client Comm Server Remote Comp. Remote Comp. Heterogeneous Or Federated Databases

30. Range of Database Applications  PC databases Usually for individual Usually for individual  Workgroup databases Small group use where everyone has access to the database over a LAN Small group use where everyone has access to the database over a LAN  Departmental databases Larger than a workgroup – but similar Larger than a workgroup – but similar  Enterprises databases For the entire organization over an intranet (or sometimes the internet) For the entire organization over an intranet (or sometimes the internet)

31. Terms and Concepts  Database activities: Create Create Add new data to the databaseAdd new data to the database Read Read Read current data from the databaseRead current data from the database Update Update Update or modify current database dataUpdate or modify current database data Delete Delete Remove current data from the databaseRemove current data from the database

32. Terms and Concepts  Enterprise Organization Organization  Entity Person, Place, Thing, Event, Concept... Person, Place, Thing, Event, Concept...  Attributes Data elements (facts) about some entity Data elements (facts) about some entity Also sometimes called fields or items or domains Also sometimes called fields or items or domains  Data values instances of a particular attribute for a particular entity instances of a particular attribute for a particular entity

33. Terms and Concepts  Records The set of values for all attributes of a particular entity The set of values for all attributes of a particular entity “tuples” or “rows” in relational DBMS “tuples” or “rows” in relational DBMS  File Collection of records Collection of records “Relation” or “Table” in relational DBMS “Relation” or “Table” in relational DBMS

34. Terms and Concepts  Key an attribute or set of attributes used to identify or locate records in a file an attribute or set of attributes used to identify or locate records in a file  Primary Key an attribute or set of attributes that uniquely identifies each record in a file an attribute or set of attributes that uniquely identifies each record in a file

35. Terms and Concepts  Data Administration Responsibility for the overall management of data resources within an organization Responsibility for the overall management of data resources within an organization  Database Administration Responsibility for physical database design and technical issues in database management Responsibility for physical database design and technical issues in database management  Data Steward Responsibility for some subset of the organization’s data, and all of the interactions (applications, user access, etc.) for that data Responsibility for some subset of the organization’s data, and all of the interactions (applications, user access, etc.) for that data

36. Figure 1-11 Components of the database environment

37. Components of the Database Environment   CASE Tools – computer-aided software engineering   Repository – centralized storehouse of metadata   Database Management System (DBMS) – software for managing the database   Database – storehouse of the data   Application Programs – software using the data   User Interface – text and graphical displays to users   Data Administrators – personnel responsible for maintaining the database   System Developers – personnel responsible for designing databases and software   End Users – people who use the applications and databases

38. Evolution of DB Systems   Flat files - 1960s - 1980s   Hierarchical – 1970s - 1990s   Network – 1970s - 1990s   Relational – 1980s - present   Object-oriented – 1990s - present   Object-relational – 1990s - present   Data warehousing – 1980s - present   Web-enabled – 1990s - present

39. Example of a Database

40. The SQL Query Language   To find all supliers in London   Select *   FROM S   Where city=“London”   To find just names and status, replace the first line:   SELECT sname, status