1. The University of Akron Dept of Business Technology Computer Information Systems Intro to Database Management 2440: 180 Database Concepts Instructor: Enoch E. Damson

2. 2Introduction to Database Management File Processing Systems Developed to store, manipulate, and retrieve large files of data in the early stages of the introduction of computers into the business world Developed to store, manipulate, and retrieve large files of data in the early stages of the introduction of computers into the business world In the file processing environment: In the file processing environment: Files are used to store data in organizations Files are used to store data in organizations Each user area has its own collection of files independent of other files Each user area has its own collection of files independent of other files

3. 3Introduction to Database Management File Processing Keywords Byte (character) - a group of bits (8 bits) Byte (character) - a group of bits (8 bits) Field – a collection of characters Field – a collection of characters Record – a collection of fields Record – a collection of fields File – a collection of records File – a collection of records

4. 4Introduction to Database Management Disadvantages of File Processing Systems Program-Data Dependence – changes to a file structure requires changes to file descriptions for programs that access the file Program-Data Dependence – changes to a file structure requires changes to file descriptions for programs that access the file Data Redundancy – duplicate data files often: Data Redundancy – duplicate data files often: Wastes space Wastes space Makes updates cumbersome and time-consuming Makes updates cumbersome and time-consuming Lead to data inconsistencies Lead to data inconsistencies Result in loss of data integrity Result in loss of data integrity

5. 5Introduction to Database Management Disadvantages of File Processing Systems… Limited Data Sharing – each application has its own private files which limits data sharing Limited Data Sharing – each application has its own private files which limits data sharing Poor Programmer Productivity – new applications require the developer to start designing from scratch Poor Programmer Productivity – new applications require the developer to start designing from scratch Excessive Program Maintenance – heavy program maintenance loads are created based on the disadvantages above Excessive Program Maintenance – heavy program maintenance loads are created based on the disadvantages above

6. 6Introduction to Database Management Database Processing Emphasizes the integration and sharing of data throughout an organization Emphasizes the integration and sharing of data throughout an organization The term database system refers to an organization of components that define and regulate the collection, storage, management, and use of data within a database environment The term database system refers to an organization of components that define and regulate the collection, storage, management, and use of data within a database environment A database system is simply a database and a database management system (DBMS) put together A database system is simply a database and a database management system (DBMS) put together

7. 7Introduction to Database Management What is a Database? An organized collection of data (and metadata) about the activities of entities and the relationships among these entities An organized collection of data (and metadata) about the activities of entities and the relationships among these entities

8. 8Introduction to Database Management Database Definition Keywords Data – raw facts Data – raw facts Information – processed data Information – processed data Metadata – data that describe the properties of other data Metadata – data that describe the properties of other data The properties include: The properties include: Data definitions Data definitions Data structures Data structures Rules or constraints Rules or constraints

9. 9Introduction to Database Management Database Definition Keywords… Entity – a person, thing, place, or event for which data is collected Entity – a person, thing, place, or event for which data is collected May also be known as a relation, table or file May also be known as a relation, table or file E.g., customer, orders etc could be entities in a database E.g., customer, orders etc could be entities in a database Attribute – a property of an entity Attribute – a property of an entity May also be termed a field or a column May also be termed a field or a column E.g., a customer entity may have name, address etc E.g., a customer entity may have name, address etc Relationship – association between entities Relationship – association between entities

10. 10Introduction to Database Management Types of Entity Relationships One-to-many relationships One-to-many relationships E.g., each department has many employees but each employee belongs to only one department E.g., each department has many employees but each employee belongs to only one department Many-to-many relationships Many-to-many relationships E.g., each student can take many courses and each course could be taken by many students E.g., each student can take many courses and each course could be taken by many students One-to-one relationships One-to-one relationships E.g., each team is managed by a coach and a coach manages a single team E.g., each team is managed by a coach and a coach manages a single team

11. 11Introduction to Database Management Entities & Attributes

12. 12Introduction to Database Management Entity Relationship One-to-many relationship One-to-many relationship

13. 13Introduction to Database Management Records A collection of fields A collection of fields May also be termed a row or a tuple May also be termed a row or a tuple Below is are examples of two entities with records Below is are examples of two entities with records

14. 14Introduction to Database Management Other Database Definitions A database is: A database is: Self-describing (metadata) – does not rely on a separate structure for information (logically complete) Self-describing (metadata) – does not rely on a separate structure for information (logically complete) Integrated (Related) – contains relationships among entities Integrated (Related) – contains relationships among entities Shared – more than one user has access to the data Shared – more than one user has access to the data

15. 15Introduction to Database Management Entity-Relationship Diagram Visual representation of a database Visual representation of a database Various versions of entity-relationship diagrams exist Various versions of entity-relationship diagrams exist Rectangles represent entities Rectangles represent entities Lines represent relationships between connected entities Lines represent relationships between connected entities Other forms have circles representing attributes Other forms have circles representing attributes

16. 16Introduction to Database Management Entity-Relationship Diagram…

17. 17Introduction to Database Management Database Management System (DBMS) Software that manages a database Software that manages a database Three basic functions include: Three basic functions include: Defining a database – specifying the metadata (data types, constraints, etc) for data storage Defining a database – specifying the metadata (data types, constraints, etc) for data storage Constructing a database – storing data Constructing a database – storing data Manipulating a database – querying the database for specific data, updating the database and generating reports from the data Manipulating a database – querying the database for specific data, updating the database and generating reports from the data

18. 18Introduction to Database Management Types of DBMSs Popular DBMSs include: Popular DBMSs include: Access (by Microsoft) Access (by Microsoft) Oracle (by Oracle) Oracle (by Oracle) DB2 (by IBM) DB2 (by IBM) SQL Server (by Microsoft) SQL Server (by Microsoft) MySQL MySQL dBASE dBASE Paradox Paradox Informix Informix

19. 19Introduction to Database Management Different DBMS Usage Using a DBMS directly Using a DBMS directly Using a DBMS through another program Using a DBMS through another program

20. 20Introduction to Database Management Components of a DBMS A DBMS is evaluated based on the: A DBMS is evaluated based on the: Database engine Database engine Data dictionary Data dictionary Query processor Query processor Report writer Report writer Forms generator Forms generator Communication & integration utilities Communication & integration utilities Security utilities Security utilities

21. 21Introduction to Database Management Components of a DBMS… Database engine – responsible for storing, retrieving, and updating the data Database engine – responsible for storing, retrieving, and updating the data Data dictionary – holds the metadata of the data tables Data dictionary – holds the metadata of the data tables Query processor – allows users to store and retrieve data with the use of a query language Query processor – allows users to store and retrieve data with the use of a query language

22. 22Introduction to Database Management Components of a DBMS… Report writer – generates database reports Report writer – generates database reports Forms generator – helps to create input forms for tasks such as data entry Forms generator – helps to create input forms for tasks such as data entry Application generator – has tools (menus, toolbar generators, etc) to assist the developer in creating a complete application Application generator – has tools (menus, toolbar generators, etc) to assist the developer in creating a complete application

23. 23Introduction to Database Management Components of a DBMS… Communication and integration utilities – help data storage and usage on different machines, from different locations Communication and integration utilities – help data storage and usage on different machines, from different locations E.g., modern operating systems and independent networks, including the Internet, have made it easier to connect databases running from different locations E.g., modern operating systems and independent networks, including the Internet, have made it easier to connect databases running from different locations Security utilities – establish and maintain security access controls Security utilities – establish and maintain security access controls

24. 24Introduction to Database Management DBMS Data Models A DBMS allows users to define the data to be stored in terms of a data model A DBMS allows users to define the data to be stored in terms of a data model Data model – a collection of high-level data description constructs that hide many low-level storage details Data model – a collection of high-level data description constructs that hide many low-level storage details Has 2 components: Has 2 components: Structure – the way systems structure data Structure – the way systems structure data Operations – facilities given to a DBMS user to manipulate data within a database Operations – facilities given to a DBMS user to manipulate data within a database

25. 25Introduction to Database Management Types of Data Models Hierarchical model Hierarchical model Network model Network model Relational model Relational model Object-Oriented model Object-Oriented model

26. 26Introduction to Database Management The Hierarchical Model Has a collection of records (hierarchies) perceived as organized to conform to a top-down tree structure Has a collection of records (hierarchies) perceived as organized to conform to a top-down tree structure The structure is perceived logically rather than physically The structure is perceived logically rather than physically Top layer is perceived as the parent of the segment directly beneath it Top layer is perceived as the parent of the segment directly beneath it A segment beneath another segment is a child segment A segment beneath another segment is a child segment Relatively fast approach (as long as data is accessed from top to bottom) Relatively fast approach (as long as data is accessed from top to bottom) Can provide some difficulties in data search, especially items in the bottom or middle of the hierarchy Can provide some difficulties in data search, especially items in the bottom or middle of the hierarchy Some hierarchical DBMSs include: Generalized Update Access method (GUAM), Information Management System (IMS), DL/I, Integrated Data Store (IDS), IDMS Some hierarchical DBMSs include: Generalized Update Access method (GUAM), Information Management System (IMS), DL/I, Integrated Data Store (IDS), IDMS

27. 27Introduction to Database Management The Network Model Similar to the hierarchical model Similar to the hierarchical model Primary goal was to address the need to: Primary goal was to address the need to: Represent complex data relationships more effectively than the hierarchical model Represent complex data relationships more effectively than the hierarchical model Improve on database performance Improve on database performance Impose database standards Impose database standards Perceived as a collection of data sets Perceived as a collection of data sets Each set is composed of at least two record types: Each set is composed of at least two record types: owner record (equivalent to the hierarchical model’s parent) owner record (equivalent to the hierarchical model’s parent) member record (equivalent to the hierarchical model’s child) member record (equivalent to the hierarchical model’s child)

28. 28Introduction to Database Management The Relational Model E. F. Codd of IBM originated the relational model approach in the 1970s E. F. Codd of IBM originated the relational model approach in the 1970s Has been the predominant method for data storage Has been the predominant method for data storage The central data description construct is a table (called “relation” by Dr. Codd) The central data description construct is a table (called “relation” by Dr. Codd) Relation (entity) - a set of records, with the same number and type of fields Relation (entity) - a set of records, with the same number and type of fields Some relational DBMSs include: DB2, Oracle, Sybase, Paradox, dBASE, Access, MySQL, SQL Server Some relational DBMSs include: DB2, Oracle, Sybase, Paradox, dBASE, Access, MySQL, SQL Server

29. 29Introduction to Database Management The Object-Oriented Model Relatively new and evolving method of organizing data Relatively new and evolving method of organizing data The goal of the model is to define objects that can be reused in many programs, to save time and reduce errors The goal of the model is to define objects that can be reused in many programs, to save time and reduce errors The objects have: The objects have: Properties (or attributes) Properties (or attributes) Methods (or functions) Methods (or functions) Some Object-Oriented DBMSs include: Gemstone, Objectivity/DB, Versant Some Object-Oriented DBMSs include: Gemstone, Objectivity/DB, Versant

30. 30Introduction to Database Management Types of Database Systems The DBMS, on which the database system is based, can be classified according to the: The DBMS, on which the database system is based, can be classified according to the: Number of users Number of users Site location Site location Type and extent of use Type and extent of use

31. 31Introduction to Database Management Database System Types Based on Number of Users Single-user database system – supports only one user at a time Single-user database system – supports only one user at a time E.g. Desktop Databases E.g. Desktop Databases Multi-user database system – supports multiple users at the same time Multi-user database system – supports multiple users at the same time E.g. E.g. Workgroup databases Workgroup databases Department databases Department databases Enterprise databases Enterprise databases

32. 32Introduction to Database Management Database System Types Based on Number of Users… Desktop Databases – single-user databases that run on a personal computer Desktop Databases – single-user databases that run on a personal computer Workgroup Databases – multi-user databases that support a relatively small number of users (usually less than 25 users) Workgroup Databases – multi-user databases that support a relatively small number of users (usually less than 25 users) Each member of the workgroup has a desktop computer and the computers are linked by means of a local area network (LAN) Each member of the workgroup has a desktop computer and the computers are linked by means of a local area network (LAN) The database is stored on a central device called the database server, connected to the network to make each group member obtain access to the shared data The database is stored on a central device called the database server, connected to the network to make each group member obtain access to the shared data

33. 33Introduction to Database Management Database System Types Based on Number of Users… Department Databases – similar to workgroup databases but with a little larger number of group members (typically between 25 and 100 members) and responsible for a more diverse range of functions Department Databases – similar to workgroup databases but with a little larger number of group members (typically between 25 and 100 members) and responsible for a more diverse range of functions Enterprise Databases – multi-user databases with its scope on the entire organization or enterprise Enterprise Databases – multi-user databases with its scope on the entire organization or enterprise Arguably, the most important type of enterprise database today is called a data warehouse Arguably, the most important type of enterprise database today is called a data warehouse Data warehouse – an integrated decision support database with content derived from various operational databases Data warehouse – an integrated decision support database with content derived from various operational databases

34. 34Introduction to Database Management Database System Types Based on Site Location Ce ntralized database system – supports a database located at a single site Ce ntralized database system – supports a database located at a single site Distributed database system – supports a database distributed across several different sites Distributed database system – supports a database distributed across several different sites

35. 35Introduction to Database Management Database System Types Based on Extent of Usage Transactional (production) database system – supports “immediate response” transactions like product or service sales, payments, etc Transactional (production) database system – supports “immediate response” transactions like product or service sales, payments, etc Decision support database system – focuses on the production of information required for tactical or strategic decisions such as sales forecasting, pricing, market positioning, etc Decision support database system – focuses on the production of information required for tactical or strategic decisions such as sales forecasting, pricing, market positioning, etc

36. 36Introduction to Database Management Other Database Systems The past few years have produced advances in technology leading to exciting new applications of database systems such as: The past few years have produced advances in technology leading to exciting new applications of database systems such as: Multimedia databases Multimedia databases Geographic information systems Geographic information systems Data warehouses Data warehouses

37. 37Introduction to Database Management Other Database Systems… Multimedia databases – store pictures, video clips, and sound messages Multimedia databases – store pictures, video clips, and sound messages Geographic information systems (GIS) – store and analyze maps, weather data, and satellite images Geographic information systems (GIS) – store and analyze maps, weather data, and satellite images Data warehouses and on-line analytical processing (OLAP) or on-line transaction processing (OLTP) systems – used to extract and analyze useful information from very large databases for decision- making Data warehouses and on-line analytical processing (OLAP) or on-line transaction processing (OLTP) systems – used to extract and analyze useful information from very large databases for decision- making

38. 38Introduction to Database Management Advantages of Database Processing Economy of Scale - cost of several combined operations becomes less than the cost of individual operations Economy of Scale - cost of several combined operations becomes less than the cost of individual operations More Information from Same Data - users are able to acquire additional information from a pool of data More Information from Same Data - users are able to acquire additional information from a pool of data Shared Data - several users can gain access to the same data Shared Data - several users can gain access to the same data Balanced Conflicting Requirements - Database Administrators structure databases to benefit a group of users, rather than individual users in an organization Balanced Conflicting Requirements - Database Administrators structure databases to benefit a group of users, rather than individual users in an organization

39. 39Introduction to Database Management Advantages of Database Processing… Enforcement of Standards - DBAs set standards for data access and usage Enforcement of Standards - DBAs set standards for data access and usage E.g., illegal data retrieval E.g., illegal data retrieval Controlled Redundancy - Databases are structured to control redundancies Controlled Redundancy - Databases are structured to control redundancies Data Consistency - Controlled redundancies ensures data consistency Data Consistency - Controlled redundancies ensures data consistency Data Integrity - Integrity constraints ensure data integrity Data Integrity - Integrity constraints ensure data integrity

40. 40Introduction to Database Management Advantages of Database Processing… Data Security - unauthorized users can be prevented from database access Data Security - unauthorized users can be prevented from database access Flexibility and Responsiveness - requests from multiple users or areas are granted in an efficient, effective, and flexible manner by DBMSs Flexibility and Responsiveness - requests from multiple users or areas are granted in an efficient, effective, and flexible manner by DBMSs Increased Programmer Productivity - 4GLs have cut down the time spent by programmers and increased production enormously Increased Programmer Productivity - 4GLs have cut down the time spent by programmers and increased production enormously

41. 41Introduction to Database Management Advantages of Database Processing… Improved Program Maintenance - changes to existing data structures might not need maintenance to existing programs since programs are independent of the structure of a database Improved Program Maintenance - changes to existing data structures might not need maintenance to existing programs since programs are independent of the structure of a database Data Independence - the structure of a database can change without requiring the application programs to change Data Independence - the structure of a database can change without requiring the application programs to change The structure of the database is independent from application programs The structure of the database is independent from application programs

42. 42Introduction to Database Management Disadvantages of Database Processing Size - DBMSs tend to occupy more disk space and memory Size - DBMSs tend to occupy more disk space and memory Complexity - the several functions offered by a DBMS can make it a complex product for programmers to familiarize with Complexity - the several functions offered by a DBMS can make it a complex product for programmers to familiarize with Cost - some DBMSs are very expensive (esp. client/server DBMSs) Cost - some DBMSs are very expensive (esp. client/server DBMSs)

43. 43Introduction to Database Management Disadvantages of Database Processing… Additional Hardware Requirement - hardware resources are required for multi-user DBMSs Additional Hardware Requirement - hardware resources are required for multi-user DBMSs Higher Impact of a Failure - failure in a DBMS component can affect several users and other components of the DBMS Higher Impact of a Failure - failure in a DBMS component can affect several users and other components of the DBMS Difficulty in Data Recovery - with the size and complexity of a database, recovery becomes difficult in case of data loss Difficulty in Data Recovery - with the size and complexity of a database, recovery becomes difficult in case of data loss