1. Organizing Data and Information

2. What is Data?? • Numbers, characters, images, or other method of recording,in a form which can be assessed by a human or (especially)input into a computer, stored and processed there, ortransmitted on some digital channel. • Data on its own has no meaning, only when interpreted by somekind of data processing system does it take on meaning andbecome information. • People or computers can find patterns in data to perceiveinformation, and information can be used to enhanceknowledge. Since knowledge is prerequisite to wisdom, wealways want more data and information.

3. What is Data??

4. Database Concepts • Data • is a valuable resource • collection of facts/figures/observations • storing, organizing, retrieving, sorting, maintaining data are important activities. • to organize data you must understand:

5. Some Key Terminology • FIELDS: • A field is a single attribute of an entity • Entity can be person, place, object, event, idea • Field Names: Each field is given a name • Examples: Name, Age, Salary • Field Value: • Specific value/content of a field name • Ex.: “Joe Blow”, 30, 23000

6. Some Key Terminology • RECORDS: Group of related field values belonging to a given entity under consideration • FILE: Group of related records • DATABASE: Group of related files

7. TCUID Preferred Last FullName GrdBasis Status Units 106-501-303 Josie Benor Benor,Josie Leiser GRD Enrolled 3 106-407-964 Chris Bosillo Bosillo,ChristopherWayne GRD Enrolled 3 106-430-298 Michael Buono Buono,Michael Vincent GRD Enrolled 3 106-379-381 Christopher Byars Byars,Christopher R. GRD Enrolled 3 106-373-583 Katie Clement Clement,Katie R. GRD Enrolled 3 106-387-806 Cole Davis Davis,Cole St.Clair GRD Enrolled 3 106-353-873 James Day Day,James Curtis GRD Enrolled 3 106-360-584 Emery Dodson Dodson,Emery Anne GRD Enrolled 3 106-414-752 Hilary Felton Felton,HilarySchrader GRD Dropped 3 Section 035 Fields: Field Names: Field Value: Records

8. Database File Record Field Character Bits (0 or 1) Data Hierarchy

9. Data Hierarchy

10. Data Management • Concerned with • Data accuracy • reliable source of data • reliable data entry • timeliness. • Security • protecting data to keep it from being misused or lost (authorized access, backup) • Data maintenance • procedures used to keep data current (adding, changing, deleting)

11. The Traditional Approach To Data Management

12. Limitations of Files • Data Redundancy – duplicate fields in multiple files • Data Inconsistency – identical fields have different data • Data Isolation – inaccessibility of data from other applications • Security – nonexistent • Data Integrity – accuracy of data in records

13. Database • A Database - an organized collection of related data that can service many applications at the same time. • A collection of data is not per se a database. • Organized means that you can easily find what you want. • Related means that the data have significance when viewed together.

14. Data Entities and Attributes • Entity • Generalized class of people, places, or things for which data is collected, stored, and maintained • Examples of entities include employees, customers, and inventory • Attributes • A characteristic of an entity • For example, employee number, last name, first name, hire date, and department number are attributes for an employee

15. Keys • Key: • A field or set of fields in a record that is used to identify the record • Primary Key • A field or set of fields that uniquely identifies the record

16. Keys and Attributes

17. The Database Approach to Data Management

18. Improved strategic use of corporate data Reduced data redundancy Improved data integrity Easier modification and updating Data and program independence Better access to data and information Standardization of data access Framework for program development Better overall protection of the data Shared data and information resources Advantages of Database Approach

19. Disadvantages of Database Approach • Relatively high cost of purchasing and operating a DBMS in a mainframe operating environment • Increased cost of specialized staff • Increased vulnerability

20. Database Models • Hierarchical (tree) • Network • Relational

21. Hierarchical Database Model

22. Network Database Model

23. Relational Database Model

24. A Relational Database Model Link via a common field between tables

25. Relational database and keys • A relational database is a collection of tables that are related to one another based on a common field. • A field, or a collection of fields, is designated as the primary key. • The primary key uniquely identifies a record in the table. • When the primary key of one table is represented in a second table to form a relationship, it is called a foreign key.

26. The primary key in the Employer table (EmployerID) is the common field that relates this table to the Position table. PositionID is the primary key in the Position table. The EmployerID field is a foreign key in this table. Primary keys can only have one occurrence in a table. Foreign keys may have multiple occurrences. Relating tables using a common field

27. Linking Database Tables to Answer an Inquiry