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Agricultural to Industrial to Information Age Data –Bits and Bytes –e.g. 5184424028 Information –organized and presented in a form suitable for decision.

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Presentation on theme: "Agricultural to Industrial to Information Age Data –Bits and Bytes –e.g. 5184424028 Information –organized and presented in a form suitable for decision."— Presentation transcript:

1 Agricultural to Industrial to Information Age Data –Bits and Bytes –e.g Information –organized and presented in a form suitable for decision making –e.g. (518) Knowledge

2 Desirable Attributes of Information Shareable Transportable Secure Accurate Timely Relevant

3 Where do companies get information from? They buy it –Consultants, publications, news services etc. They generate it –Computer systems (programs process data stored in databases) –Employees (apply experience and intelligence)

4 Where do we store Intangible Assets -- Information? In peoples heads On paper In card-files In computers

5 Entities, Attributes, and Relationships Entity – a person, place, thing, or event Attribute – a property of an entity –For the entity Person, attributes could include eye color and height Relationship – an association between entities –Publishers are related to the books they publish, and a book is related to its publisher

6 Terminology Fields - attribute Domain -Description of allowed values for an attribute Records - logically connected set of one or more fields. Files - collection of records

7 History of Data Processing Manual record-keeping –High labor costs and human errors Data file – stores information on a single entity and the attributes of that entity Database – a structure that can store information about multiple types of entities, the attributes of these entities, and the relationships among the entities

8 Limitations of File-Based Systems Separation and Isolation of Data Duplication of Data Data dependence Incompatibility of files Fixed queries / proliferation of application programs / pressure on DP staff

9 Database A self-describing collection of integrated records Properties of a Database: –It represents some aspect of the real world –It is a logically coherent collection of data with some inherent meaning –It is designed, built, and populated with data for a specific purpose –It has users and applications

10 Spreadsheet or Database? Data size Data storage format Data structure –extent to which relationships among data items are fixed Data sharing Data control –degree of data input editing and validating

11 StaticDynamic Low High Structure Sharing Control Low High SOLUTION SpreadsheetDatabase Either DB

12 DBMS A software system that : –Enables users to define, create and maintain the database –Provides controlled access to this database

13 DBMS components Machine –Hardware –Software Data Human –Procedures –People

14 Data Life Cycle Data acquisition –data modeling and populating with ultimate goal of storing data Data use –Combines data that has been previously stored and interprets output in a decision making context (Data Warehousing)

15 Data acquisition Logical database design –E/R diagrams, normalization, database models Physical database design –Integrity constraints, indexes, denormalization Populating the database –data entry, import, download Update records –data dictionary, metadata

16 Data Use Define view –Query design, DDL (SQL or QBE) Retrieve data –Query performance and optimization, concurrency controls Manipulate data –Sort, aggregate, classify, analyze Present results –Reports, forms

17 Access Database Objects Tables –Stores data as records Queries –Answers questions about the database Forms –Presents data using a customized layout Reports –Formats the data (primarily for printouts) Macros –Used to automate repetitive tasks Modules Pages

18 Users Administrators –Data Administrator –Database Administrator Database designers –Conceptual and logical design (WHAT?) –Physical design (HOW?) Application programmers End users –naïve (e.g checkout assistant) –sophisticated

19 Everyday Database Systems Supermarket Credit card Travel Agent Insurance Library University

20 Applications of DBMS Airline reservations systems –Reservations (customer name, assigned seat) –Flights (airports, arrival and departures) –Tickets (prices, requirements, availability) Banking systems –Customers (names, addresses, accounts, loans) Corporate records –Accounts (payable, receivable) –Employees (names, addresses, salary, benefits)

21 Creating a Table in Access Datasheet view –To add, delete or edit records Design View –To define table the initially and specify its fields

22 Custom Tables Validation rules Input masks Default values Lookup fields Format

23 Advantages of Database Processing Getting more information from the same amount of data –When all the data for various systems are stored in a single database, the information becomes available, as well as the process of retrieving the information can be quick and easy

24 Advantages of Database Processing Sharing of data –Several users can have access to the same piece of data (Concurrency control allows shared access) Balancing conflicting requirements –A person or group, often called Database Administration/Administrator (DBA) can structure the database in such a way that it benefits the entire organization, not just a single group

25 Advantages of Database Processing Controlling redundancy –Not only saves space, but makes the updating process easier Consistency –Consistency is a direct result of redundancy, so by reducing redundancy, there is much less potential for this sort of inconsistency with the database approach

26 Advantages of Database Processing Integrity –An integrity constraint is a rule that must be followed by data in the database Example: Not allowing a persons age to be lower than zero Security –The prevention of access to the database by unauthorized users –Recovery control restores the data to previous consistent state after hardware/software failure

27 Advantages of Database Processing Increasing productivity –A good DBMS comes with many features that allow users to gain access to data without having to do any programming at all Data independence –A property that allows the structure of a database to be changed without the programs that access the database having to change

28 Disadvantages of Database Processing DBMS size –DBMSs are large programs that occupy a large amount of disk space as well as internal memory DBMS complexity –The complexity and breadth of the functions provided by a DBMS make it a complex product to use

29 Disadvantages of Database Processing Greater impact of a failure –A failure on the part of any one user that damages the database in some way may affect all the other users on the system More difficult recovery –If the database is being updated by a large number of users, all updates must be redone since the time of its restoration

30 When can an organization justify a database? Application needs are constantly changing Rapid access is required for ad hoc queries Need to reduce long lead times and high development costs for new systems Data elements are shared by users Need to communicate and relate data across functional and departmental boundaries Need to improve quality of data resources and control access to them

31 History of DBMS IBM developed the Generalized Update Access Method (GUAM) in 1964 for North American Rockwell, the prime contractor for the APOLLO project GUAM was made available for the general public under the name Data Language/I (DL/I) in 1966

32 History of DBMS DL/I became the data management component for the Information Management System (IMS), which was the dominant DBMS for many years In the mid-1960s, General Electric developed Integrated Data Store (I-D-S)

33 History of DBMS First generation –Hierarchical and network models Second generation –Relational models Third generation –Object oriented models

34 Data Models Record Based –Hierarchical (60s) –Network (70s) –Relational (80s) Object Based –Entity-Relationship (70s) –Semantic data models (80s) –Object-oriented (90s)

35 Record-Based Data Models Hierarchical –Parent-child relationships with only one parent (N:1 relationships are not supported) Network –Extends hierarchical model by allowing multiple parents –Associations are created via pointers Relational

36 Hierarchical Model Perceived by the user as a collection of hierarchies, or trees More restrictive structure than a network model GUAM, DL/I, and IMS are examples of DBMSs that conform to the hierarchical model

37 Network Model Perceived by the user as a collection of record types and relationships between these record types I-D-S is an example of a DBMS that conforms to the network data model

38 Assignment 1 MS Access 2000 Pages AC 2.34 –2.36 #1-16


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