Introduction to Management Information Systems Chapter 4 Database Processing HTM 304 Fall 07

Learning Objectives Know purpose of database processing List components of a database system Understand important database terms Know elements of the entity-relationship model Understand general nature of database design

Purpose of a Database Keep track of things with more than one theme

One Theme Spread Sheet

Multi-theme Database All three records for one student (student is the link of different themes) Student Score Email records office visits

Database Hierarchy Bytes: the basic elements which compose of database Fields (Columns). Name, number or characters that describe an aspect of a business object or activity. e.g. Student Numbers, Student Names, Midterm Scores, etc. Record (Rows). Collection of related data fields. e.g. 000054323 Jenny White 89. File (or Table). Collection of related records. e.g. Student Score Table, Student Office Visit Table, Student Email Record Table Database. Collection of integrated and related files + Relations between (among) tables + structure of data. The relations and structures are called metadata

Components of Database Tables or Files + Relationships among Rows in Table Metadata Database = How to effectively organize and process raw data is the key to a successful database design and an Information System design.

Student Table Records/Rows Columns/Fields

Poorly Designed Table Pros and cons? Common Practice in Excel In Database Design, the record will be split into 2 records: Jones Feb 1, 2002 Jones@ourcompany.com 100 Finance Jones Feb 1, 2002 Jones@ourcompany.com 100 Accounting Pros and cons?

Relationships The records in different tables are connected by certain relationships – relational databases Key – column or group of columns that identifies a unique row in a table For example: Student Number is key of Student table The key insures no repeated records Every table MUST have a key Foreign key – non-key column or field in one table that links to a primary key in another table Student Number in Email and Office_Visit tables Foreign keys link records from different tables together as one compound record

Examples of Relationships Foreign Key Key Foreign Key

Relationships among Rows Review Components Tables or Files + Relationships among Rows Metadata Database =

Metadata Metadata are data that describe data (Format, Field Properties, etc.) Makes databases much more useful No one needs to guess, remember, or record what is in database Make databases easy to use for authorized and unauthorized purposes

Exercise: Use Access to setup a data table Create a database file (*.mdb) Create table in design view All tables are in one database file First create the table in design view Specify the fields (column headers) Specify the types of the fields, and other properties Specify which field is the key! Finish design view -- Close the design view Fill in records in the table Double click the table to enter editing view Enter records Try enter repeated keys, it won’t let you! Why? Use Student Visit example

DB Application Systems Components Pure database data correct, but raw form not pertinent or useful DB applications make DB data accessible and useful Users employ DB applications Forms Formatted reports Queries (SQL language) Application programs Each calls on DBMS to process DB tables

DB Application System Components DBMS (Database Management System) A program used to create, process, and administer a database. Database developers use the DBMS to create tables, relationships, and other structures in the database.

Enterprise DBMS Process large organizational and workgroup databases Support many, perhaps thousands, of users and many different database applications Support 24/7 operations and can manage dozens of different magnetic disks with hundreds of gigabytes or more data IBM’s DB2, Microsoft’s SQL Server, and Oracle are examples of enterprise DBMS products

Personal DBMS Designed for smaller, simpler database applications. Used for personal or small workgroup applications that involve <100 users, normally fewer than 15 Bulk of personal databases have only a single user Microsoft Access only available personal DBMS

Language used in DBMS SQL: Structured Query Language An international standard language for processing a database: Data Manipulation/Definition and Data Queries Data Manipulation Data Queries: See later. INSERT INTO StudentTable ([Student Number], [Student Name], Hw1, Hw2, MidTerm) VALUES (1000, ‘Joe Black’, 90, 85, 88) UPDATE StudentTable SET MidTerm = ’90’ WHERE Student Number = ‘1000’ DELETE FROM StudentTable WHERE MidTerm = NULL

Exercise: Below shows the original table. Write down the resulting table after executing the following SQL command: UPDATE StudentTable SET LetterScore = ’A’ WHERE Score >= ‘90’. Original Table: StudentTable StudentNumber StudentName Score LetterScore 1000 Justin Frank 89 -- 2000 Dennis Wilson 60 3000 Sheldon Benson 92 4000 Gordon Black 87 5000 Jimmy Foxx 96 Exercise: write down all the other letter scores based on certain criterion.

DB Application System Components D B M S Database Applications: collection of forms, reports, queries, and application programs that process a database. A database may have one or more applications, and each app. may have one ore more users…(Page 84) DBMS (Database Management System) A program used to create, process, and administer a database. Database developers use the DBMS to create tables, relationships, and other structures in the database.

Multiple Database Applications Think how the school uses student information?

Form – A structured way to edit and view data

Example Student Report Read Only. No Editing

Query Use SQL to search through the database and produce certain results. SELECT (certain attributes) FROM (certain database tables) WHERE (conditions) SELECT STUDENT Name, MIDTERM FROM STUDENTTABLE WHERE MIDTERM>90

Exercise: Write down the results when using the following query command on the following original data table: SELECT MIDTERM FROM STUDENTTABLE WHERE MIDTERM>90 SELECT Student Name FROM STUDENTTABLE WHERE MIDTERM<70 SELECT Student Name, Student Number, HW1, HW2, MidTerm FROM STUDENTTABLE WHERE MidTerm > (HW1+HW2)/2

DB Application System Components

Database Development Process E-R Modeling: High level blueprint defining how data are stored structurally in the system Define users’ need through interview

E-R Modeling E-R Model: a detailed, logical representation of the data for a business. To document rules and policies of an organization that govern data.

Components in E-R Model Entity – something users want to track Examples Order, Customer, Salesperson, Item Some entities represent physical object, such as an Item or Salesperson Other entities represent a logical construct of transaction, such as Order or Contact Entities have attributes that describe characteristics of the entity Example attributes of Salesperson are SalespersonName, Email, Phone, etc.

Entities (cont) Entities have identifier, an attribute (or group of attributes) whose value is associated with 1 & only 1 entity instance OrderNumber is the identifier of Order, because only 1 Order instance has given value of OrderNumber CustomerNumber identifier of Customer If each member of sales staff has unique name, then SalespersonName is an identifier of Salesperson

Student Data Model Entities

Relationships Connects identities, allow cross entity search A line is used to represent a relationship between two entities

Three basic types of relationships One-to-one: One student can buy only one permit One permit can only purchased by one student One-to-Many: One instructor can teach many courses A course can only be taught by one instructor Crow’s foot = Many Many-to-Many: One student can take more than one course A course can be registered by multiple students Parking Permit # Date of Purchase Type of Permit Expiration Date … Student ID Name DoB Address Student Parking permit CRN Course Title Classroom Credit … Instructor ID Name Department Office instructor Course CRN Course Title Classroom Credit … Student ID Name DoB Address Student Course

Who defines the relationships? Exercise Who defines the relationships?

Exercise: Exercise 22 a) (Page 105)

Opposing Forces Guide: No, Thanks, I’ll Use a Spreadsheet I’m not buying all this stuff about databases. “I’ve tried them and they’re a pain-way too complicated to set up, and most of the time, a spreadsheet works just as well.” “No, unless you are a General Motors or Toyota, I wouldn’t mess with a database.” “You have to have professional IS people to create it and keep it running.” “Besides, I don’t really want to share my data with anyone.” “I work pretty hard to develop my client list.” “Why would I want to give it away?” “When I want something, I use Excel’s Data Filter.” “I can usually get what I need.” “Of course, I can’t still send form letters, but it really doesn’t matter.” “I get most of my sales using the phone, anyway.”

Database Security The firewall, a computing device located between a firm’s internal network and external networks, prevents unauthorized access to the internal network. For the best security, the DBMS computer should be protected by a firewall, and then all other security measures should be designed as if the firewall has been breached.

Database Security (cont) All operating systems and DBMS patches should be installed as soon as they become available. No one other than authorized operations personnel should be able to directly access the computer that runs the DBMS. The computer running the DBMS should be secured behind locked doors, and visits to that room should be recorded in a log. Most DBMS products log failed attempts to sign on and produce other usage reports as well. The database administrator (DBA) should periodically monitor such logs and reports for suspicious activity.

Database Security (cont) All major DBMS products have extensive, built-in security features. These features allow for the definition of user accounts and user roles. Each user account belongs to a specific person. A role is a generic employee function, such as payroll clerk or field salesperson. Once an account is defined, it can be assigned specific permissions, and it can also be assigned particular roles. It is important to have a plan of action for security emergencies. Disaster Recovery Plan (85%) Business Continuity Plan (<15%) The steps to be taken vary from database to database.

Ethic Guide: Nobody Said I Shouldn’t Kelly make a backup copy of his company’s database on CD and took it home and installed it on his home computer. While performing queries on the database, he found customer order information and focused in on his friend Jason’s customer order entries. Kelly noticed that Jason gave huge discounts to Valley Appliances but not to his other customers. At an after work gathering, Kelly asked Jason about the Valley Appliances discount telling him what he had been doing. When Kelly returned to work, he was fired

Class 2: E-R Modeling and Database Lab E-R Data Model The most popular technique for creating a data model. E: entity (things) R: relationship (among the entities) + business rules restricting the flow of the data Data Model: Read Problem Solving Guide: (p89a) Immanuel Kant, Data Modeler Attempts to model the “real world” Simply a model of what the data modeler perceives

5 minutes free write Social Implications of DB: Relate any of Kant’s ideas to what you learned from reading “For Some, Online Persona Undermines Resume” PRINT your name on Free Write and hand it in

More exercise Book 23 a) Create a E-R Diagram to relate all the information in the form

Translating E-R diagram into Tables (1:N) Key Step 1: Create one table for each entity Key

Translating E-R diagram into Tables (1:N) Step 2: Add Foreign Key Column to the “many entity” to represent relationship

Step 3: edit relationship Go to Tools  Relationships Add two entities Drag the “advisor name” of advisor table to the “advisor name” of student table. Close relationships

Many-to-Many Relationship Now the rule changed One advisor can supervise many students One student can have many adviser One student must have at least one advisor One advisor can have no student

Foreign Key doesn’t work for N:M relationship

Solution

Exercise: Revise the relationship of previous exercise in Access and input the above records

1:1 Relationship How to convert into tables?

Exercise Based on your E-R diagram in 23(a), construct tables and relationships in Access. Add at least three records for each table.

Importance of User Review Users are the final judges of what data the database should contain and how records relate to one another Easiest time to change database structure is during data modeling stage Once database has been constructed, loaded with data, and application forms, reports, queries, and application programs created, changing a relationship means weeks of work!

How should you review as a user? (Cont) When database developed for your use, you must carefully review data model If you don’t understand any aspect of it, ask for clarification until you do Data model must accurately reflect your view of business Do not proceed unless you are 100% comfortable with the model

Key Terms and Concepts Access Field File (Table) Attribute Foreign key Byte Foreign key Column Identifier Crow’s foot Key Database Maximum cardinality Database application system Meta Data DBMS Minimum cardinality E-R data model 1:N(one-to-many) relationship

Key Terms and Concepts (Cont.) Access Field many-to-many relationship Attribute File (Table) Oracle Byte Foreign key Query Column Identifier Personal DBMS Crow’s foot Key Record Database Maximum cardinality Relationship Database application system Meta Data Report DBMS Minimum cardinality Row E-R data model one-to-many relationship SQL Server