Introduction to Management Information Systems Chapter 4 Database Processing HTM 304 Fall 07
Dec 19, 2015
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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
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Multi-theme Database
Student Score
Student Score
Email records
Email records
officevisits
officevisits
All three records for one student(student is the link of different themes)
All three records for one student(student is the link of different themes)
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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
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Components of Database
Database
Tables or Files
+
Relationships among Rows in Table
+
Metadata
=
How to effectively organize and process raw data is the key to a successful database design and an Information System design.
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Poorly Designed Table
In Database Design, the record will be split into 2 records:Jones Feb 1, 2002 [email protected] 100 FinanceJones Feb 1, 2002 [email protected] 100 Accounting
In Database Design, the record will be split into 2 records:Jones Feb 1, 2002 [email protected] 100 FinanceJones Feb 1, 2002 [email protected] 100 Accounting
Common Practice in ExcelCommon Practice in Excel
Pros and cons?
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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
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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
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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?
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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
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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 otherstructures in the database.
DBMS (Database Management System)A program used to create, process, and administer a database. Database developers use the DBMS to create tables, relationships, and otherstructures in the database.
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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
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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
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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)
DELETE FROM StudentTable WHERE MidTerm = NULL
UPDATE StudentTable SET MidTerm = ’90’ WHERE Student
Number = ‘1000’
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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.
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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 otherstructures in the database.
DBMS (Database Management System)A program used to create, process, and administer a database. Database developers use the DBMS to create tables, relationships, and otherstructures in the database.
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)
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)
D B M S
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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
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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
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Database Development Process
E-R Modeling: High level blueprint defining how data are stored structurally in the system
Define users’ need through interview
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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.
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Components in E-R Model
Entity – something users want to trackExamples 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.
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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
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Relationships
Connects identities, allow cross entity search
A line is used to represent a relationship between two entities
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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 PurchaseType of PermitExpiration Date…
Student IDNameDoBAddress…
Student Parking permit
CRNCourse TitleClassroomCredit…
Instructor IDNameDepartmentOffice…
instructor Course
CRNCourse TitleClassroomCredit…
Student IDNameDoBAddress…
Student Course
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Opposing Forces Guide:
No, Thanks, I’ll Use a SpreadsheetI’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.”
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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.
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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.
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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.
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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
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Class 2: E-R Modeling and Database Lab
E-R Data ModelThe 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
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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
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Translating E-R diagram into Tables (1:N)
Step 2: Add Foreign Key Column to the “many entity” to represent relationship
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Step 3: edit relationship
Go to Tools RelationshipsAdd two entities
Drag the “advisor name” of advisor table to the “advisor name” of student table.
Close relationships
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Many-to-Many Relationship
Now the rule changedOne 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
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Exercise
Based on your E-R diagram in 23(a), construct tables and relationships in Access. Add at least three records for each table.
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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!
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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
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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