1. - Ahmad Al-Ghoul Data design

2. 2 learning Objectives Explain data design concepts and data structures Explain data design concepts and data structures Describe file processing systems and various types of files Describe file processing systems and various types of files Understand database systems and define the advantages of a database management system (DBMS) Understand database systems and define the advantages of a database management system (DBMS)

3. 3 Data Design Concepts Before constructing an information system, a systems analyst must understand basic design concepts, including data structures and the characteristics of file processing and database systems, including Web-based database design Before constructing an information system, a systems analyst must understand basic design concepts, including data structures and the characteristics of file processing and database systems, including Web-based database design

4. 4 Data Design Concepts The data storage function manages how data is stored and handled by programs that run the system The data storage function manages how data is stored and handled by programs that run the system Goals of data storage design Goals of data storage design Efficient data retrieval (good response time) Efficient data retrieval (good response time) Access to the information users need Access to the information users need

5. 5 Data Design Concepts Data Structures Data Structures Data Structures Data Structures A framework for organizing and storing data A framework for organizing and storing data Data Structures consist of files or tables that are linked in various ways Data Structures consist of files or tables that are linked in various ways A file or table contains data about people, places or events or any important data that the business must kept information about A file or table contains data about people, places or events or any important data that the business must kept information aboutfiletablefiletable Depending on how the system’s file and tables are organized and linked, an (IS) is called either Depending on how the system’s file and tables are organized and linked, an (IS) is called either File-oriented system: also called a file processing system, stores and manages data in one or more separate files. File-oriented system: also called a file processing system, stores and manages data in one or more separate files. File-oriented system File-oriented system Database system: consists of linked data files, also called tables, that form an overall data structure. Compared to file processing, a database environment offers greater flexibility and efficiency. Database system: consists of linked data files, also called tables, that form an overall data structure. Compared to file processing, a database environment offers greater flexibility and efficiency. Database system Database system

6. 6 Data Design Concepts Overview of File Processing Overview of File Processing Companies mainly use file processing to handle large volumes of structured data on a regular basis Companies mainly use file processing to handle large volumes of structured data on a regular basis File processing design approach was well suited to mainframe hardware and batch input File processing design approach was well suited to mainframe hardware and batch input File processing design is less common today, file processing can be more efficient and cost less than a DBMS in certain situations File processing design is less common today, file processing can be more efficient and cost less than a DBMS in certain situations

7. 7 Data Design Concepts Overview of File Processing Overview of File Processing File Processing Advantages File Processing Advantages Simplicity: the design of file processing is more simple than designing Database Simplicity: the design of file processing is more simple than designing Database Efficiency: file processing cost less and can be more speed than Database Efficiency: file processing cost less and can be more speed than Database Customization: you can customize file processing more easily and efficiently than Database because files are related with the application and it have all the data needed for that application Customization: you can customize file processing more easily and efficiently than Database because files are related with the application and it have all the data needed for that application

8. 8 Overview of File Processing Overview of File Processing Potential problems Potential problems Data redundancy: occurs when data common to two or more information systems is stored in several places. Data redundancy requires more storage space, and maintaining and updating data in several locations is expensive. Data redundancy: occurs when data common to two or more information systems is stored in several places. Data redundancy requires more storage space, and maintaining and updating data in several locations is expensive. Data redundancy Data redundancy Data integrity: Refers to the validity of data. Data integrity can be compromised in a number of ways: human errors when data is entered, errors that occur when data is transmitted from one computer to another, software bugs or viruses, hardware malfunctions, such as disk crashes and natural disasters, such as fires and floods. Data integrity: Refers to the validity of data. Data integrity can be compromised in a number of ways: human errors when data is entered, errors that occur when data is transmitted from one computer to another, software bugs or viruses, hardware malfunctions, such as disk crashes and natural disasters, such as fires and floods. Data integrity Data integrity Rigid data structure: A data structure that is hard to work with and inflexible. File-processing is rigid when compared to a typical database management system. Rigid data structure: A data structure that is hard to work with and inflexible. File-processing is rigid when compared to a typical database management system. Rigid data structure Rigid data structure Data Design Concepts

9. 9 Overview of File Processing Overview of File Processing Uses various types of files Uses various types of files Master file: In a typical file processing environment, a master file stores relatively permanent data about an entity. For example, a PRODUCT master file might contain one logical record for each product a company sells. Master file: In a typical file processing environment, a master file stores relatively permanent data about an entity. For example, a PRODUCT master file might contain one logical record for each product a company sells. Master file Master file Table file: contains reference data used by the (IS). As with master files, table files are relatively static and are not updated by the (IS). Examples include tax tables and postage rate tables Table file: contains reference data used by the (IS). As with master files, table files are relatively static and are not updated by the (IS). Examples include tax tables and postage rate tables Table file Table file Transaction file: In a typical file processing environment, a transaction file stores records that contain day-to-day business and operational data. A transaction file is an input file that updates a master file; after the update is completed, the transaction file has served its purpose. Transaction file: In a typical file processing environment, a transaction file stores records that contain day-to-day business and operational data. A transaction file is an input file that updates a master file; after the update is completed, the transaction file has served its purpose. Transaction file Transaction file

10. 10 Data Design Concepts Overview of File Processing Overview of File Processing Uses various types of files Uses various types of files Work file – scratch file: In a typical file processing environment, a work file is a temporary file created by an information system for a single task. Most often a work file is created by one process in the information system and used by another process within the same system. Work files also are called scratch files. Work file – scratch file: In a typical file processing environment, a work file is a temporary file created by an information system for a single task. Most often a work file is created by one process in the information system and used by another process within the same system. Work files also are called scratch files. Work filescratch file Work filescratch file Security file: Sequence codes are numbers or letters assigned in a specific order. Sequence codes contain no additional information other than an indication of order of entry into a system. Security file: Sequence codes are numbers or letters assigned in a specific order. Sequence codes contain no additional information other than an indication of order of entry into a system. Security file Security file History file: In a typical file processing environment, a history file is a file copy created and saved for historical or archiving purposes. New history files, unlike new security files, do not replace the old files. History file: In a typical file processing environment, a history file is a file copy created and saved for historical or archiving purposes. New history files, unlike new security files, do not replace the old files. History file History file

11. 11 Data Design Concepts Example of File Processing of an auto repair shop Example of File Processing of an auto repair shop Example of an auto repair shop that uses two separate file-oriented systems: a Job Records System (with a JOB data file) and an Employee Records System (with a MECHANIC data file). Notice that three items of information must be duplicated in both data files.

12. 12 Data Design Concepts Overview of Database Systems Overview of Database Systems Database: a collection of groupings of information that relate to each other in some way. Database: a collection of groupings of information that relate to each other in some way. A properly design database system offers a solution to the problems of file processing A properly design database system offers a solution to the problems of file processing Provides an overall framework that avoids data redundancy and supports a real-time, dynamic environment Provides an overall framework that avoids data redundancy and supports a real-time, dynamic environment In a Database environment several systems can be built and share a single database In a Database environment several systems can be built and share a single database

13. 13 Data Design Concepts Overview of Database Systems Overview of Database Systems A typical database environment might consist of a database serving five separate business systems.

14. 14 Data Design Concepts Example of a database design for the auto repair shop that links two data tables and avoids duplication. Notice that the Mechanic No field provides a link between the two tables, and information can be accessed from either table.

15. 15 Data Design Concepts Overview of Database Systems Overview of Database Systems A database management system (DBMS) is a collection of tools, features, and interfaces that enables users to add, update, manage, access, and analyze the contents of a database A database management system (DBMS) is a collection of tools, features, and interfaces that enables users to add, update, manage, access, and analyze the contents of a database The main advantage of a DBMS is that it offers timely, interactive, and flexible data access The main advantage of a DBMS is that it offers timely, interactive, and flexible data access

16. 16 Data Design Concepts Overview of Database Systems Overview of Database Systems Advantages Advantages Scalability: Scalability means that a system can be expanded, modified, or downsized easily to meet the rapidly changing needs of a business enterprise. Also known as extensibility. Scalability: Scalability means that a system can be expanded, modified, or downsized easily to meet the rapidly changing needs of a business enterprise. Also known as extensibility. Scalability Better support for client/server systems: In a client/server system, processing is distributed throughout an organization. Client/server systems require the power and flexibility of database design. Better support for client/server systems: In a client/server system, processing is distributed throughout an organization. Client/server systems require the power and flexibility of database design. Economy of scale: The inherent efficiency of high-volume processing on larger computers. Database design allows better utilization of hardware. If a company maintains an enterprise-wide database, processing is less expensive using a powerful mainframe server instead of using several smaller computers. Economy of scale: The inherent efficiency of high-volume processing on larger computers. Database design allows better utilization of hardware. If a company maintains an enterprise-wide database, processing is less expensive using a powerful mainframe server instead of using several smaller computers. Economy of scale Economy of scale

17. 17 Data Design Concepts Overview of Database Systems Overview of Database Systems Advantages Advantages Flexible data sharing: Data can be shared across the enterprise, allowing more users to view the same information in different ways Flexible data sharing: Data can be shared across the enterprise, allowing more users to view the same information in different ways Enterprise-wide application – database administrator (DBA): (DBA) typically manages a database management system (DBMS). The DBA assesses overall requirements and maintains the database for the benefit of the entire organization rather than a single department or user. Enterprise-wide application – database administrator (DBA): (DBA) typically manages a database management system (DBMS). The DBA assesses overall requirements and maintains the database for the benefit of the entire organization rather than a single department or user.database administrator (DBA)database administrator (DBA) Stronger standards: effective database administration helps ensure that standards for data names, formats, and documentation are followed uniformly throughout the organization Stronger standards: effective database administration helps ensure that standards for data names, formats, and documentation are followed uniformly throughout the organization

18. 18 Data Design Concepts Overview of Database Systems Overview of Database Systems Advantages Advantages Controlled redundancy: because the data is stored in a set of related tables, data items do not need to be duplicated in multiple locations Controlled redundancy: because the data is stored in a set of related tables, data items do not need to be duplicated in multiple locations Better security: the DBA defines authorization procedures to ensure that only legitimate users can access the database and can allow different users to have different levels of access Better security: the DBA defines authorization procedures to ensure that only legitimate users can access the database and can allow different users to have different levels of access Increased programmer productivity: programmers do not have to create the underlining file structure for the database, so they can concentrate on logical design Increased programmer productivity: programmers do not have to create the underlining file structure for the database, so they can concentrate on logical design Data independence: systems that interact with a DBMS are relatively independent of how the physical data is maintained Data independence: systems that interact with a DBMS are relatively independent of how the physical data is maintained

19. 19 Data Design Concepts Database Tradeoffs Database Tradeoffs Because DBMSs are powerful, they require more expensive hardware, software, and data networks capable of supporting a multi-user environment Because DBMSs are powerful, they require more expensive hardware, software, and data networks capable of supporting a multi-user environment More complex than a file processing system More complex than a file processing system Procedures for security, backup, and recovery are more complicated and critical Procedures for security, backup, and recovery are more complicated and critical

20. 20 Sequence Summary Files and tables contain data about people, places, things, or events that affect the information system Files and tables contain data about people, places, things, or events that affect the information system File processing systems, also called file-oriented systems, manage data stored in separate files, including master files, table files, transaction files, work files, security files, and history files File processing systems, also called file-oriented systems, manage data stored in separate files, including master files, table files, transaction files, work files, security files, and history files A database consists of linked tables that form an overall data structure A database consists of linked tables that form an overall data structure A database management system (DBMS) is a collection of tools, features, and interfaces that enable users to add, update, manage, access, and analyze data in a database A database management system (DBMS) is a collection of tools, features, and interfaces that enable users to add, update, manage, access, and analyze data in a database DBMS designs are more powerful and flexible than traditional file-oriented systems DBMS designs are more powerful and flexible than traditional file-oriented systems A database environment offers scalability, support for organization-wide access, economy of scale, data sharing among user groups, balancing of conflicting user requirements, enforcement of standards, controlled redundancy, effective security, flexibility, and data independence A database environment offers scalability, support for organization-wide access, economy of scale, data sharing among user groups, balancing of conflicting user requirements, enforcement of standards, controlled redundancy, effective security, flexibility, and data independence

21. 21 Sequence Summary In this Sequence we have In this Sequence we have Distinguished between file processing system and database system Distinguished between file processing system and database system Explained the advantages and disadvantages of file processing system Explained the advantages and disadvantages of file processing system Described the various types of files in the file processing system Described the various types of files in the file processing system Defined the term data base management system (DBMS) Defined the term data base management system (DBMS) Explained the advantages of database system Explained the advantages of database system Described the database tradeoffs Described the database tradeoffs

22. 22 Reference [1] System Analysis and Design, Sixth Edition Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt Publisher: SHELLY CASHMAN SEWIES. Publisher: SHELLY CASHMAN SEWIES.