What You'll Learn This Week

• Systems Analysis and Design
• Information Systems Development Life Cycle (SDLC)
• Database Design Process
• Computer Aided Software Engineering (CASE)
• Database Application Components
  • Data Entry Forms
  • Reports
  • Queries
  • Menus
  • Applications Code
• WWW Applications

Connolly, Begg, Holowczak	Pratt/Adamski	Elmasri/Navathe (3rd) ed.	Kroenke Book (7th ed.)	McFadden (5th ed.)
Ch. 4, 5 and 6	Ch. 1 and 6	Ch. 3 and 16	Ch. 2 and 10	Ch. 1, 2 and 10 (pg. 381-400)

Systems Analysis and Design

• The goal of Systems Analysis is to capture an accurate representation of business processes and user's perceptions of them.

• The Business Processes we are interested in are those that encompass the flow of data (input, storing, processing, output) throughout an organization.

• Problem: Even the best analysts in the world would come up with differing analyses of the same problem.

• Systems Analysis applies a structured, formal method to model and improve upon business processes.

• A Systems Analyst can act as an outside consultant brought in to address a specific system design problem; as a supporting expert; as an agent of change in an organization

Information Systems Development Life Cycle (SDLC)

1. Problem, opportunity and objective Identification
   Problems include shortcomings in present business practices that need to be corrected. Opportunities include ways to improve existing practices. Objectives identify the goal of an organization and for specific business processes.
   This may also include a feasibility analysis to see which problems, etc. can be adequately addressed.

2. Information Requirements determination or Requirements Gathering
   Determine what data and information are required to perform business functions.
   • Sampling existing data files, databases
   • Examining existing reports and forms
   • User interviewing and questionnaires
   • Prototyping

3. System Needs analysis
   System requirements that are based on data requirements and decision making processes.
   Result is a system proposal that lists the recommended actions and cost/benefits.

4. System Design
   Logical design of the information system including identification of databases (tables, columns, keys, indexes) that will store required data and applications (forms, reports, menus) that will operate on the database.

5. System Development and Documentation
   System applications are developed including data entry forms, reports, menus and queries.
   Documentation for end users is also written.

6. System Testing and Maintenance
   System is tested on real data to pinpoint faults.
   Any necessary changes are applied in this step before the system goes into production.

7. Implementation and Evaluation
   The system is put into production. End user training is performed. Users and analysis evaluate the effectiveness of the system.

• At each step of the cycle, there is an opportunity to cycle back to a prior step.
• For example, during system development, it is common to require some changes to data models developed in the system design step.
• Rapid Application Development (RAD) runs quickly through steps 1-5 for small portions of a complete application.

Database Design Process

1. Gather user and system requirements
2. Create a conceptual model of the database using the Entity Relationship model that is based on the user requirements
3. Choose a DBMS - in our case, we will use MS Access, a desktop relational DBMS.
4. Convert this conceptual model (E-R) into a logical database model - we will use the Relational model. Elmasri/Navathe book calls this Data model mapping
5. Normalize the Relational model of the database
6. Implement the normalized relations as tables in a relational database - this is the Physical Database design and implementation.

The above discussion corresponds to Elmasri/Navathe's 6 Phases for DB design (chapter 14).

Computer Aided Software Engineering (CASE)

• CASE tools can assist analysts in the SDLC.
  • Provide a repository to store information on each of the phases - excellent for comprehensive documentation of the development process.
  • Diagraming tools assist in analyst/user communications. For example, Data Flow Diagrammer and E-R Model Diagrammer.
  • Provide project management capabilities including maintenance management - impact analysis.
• However, each CASE tool supports a specific implementation of an SDLC; often in a very ridged fashion.

• Upper CASE Tools typically focus on the first 5 steps of the SDLC.
• Lower CASE Tools focus on steps 4-6 and include code generation capabilities.
• Integrated CASE Tools cover all of the steps.
• Examples: Oracle Designer (integrated)
  Visible Analyst (upper)
  IBM System Architect(formerly Popkin SA) (integrated)

• More on CASE in the System Analysis classes.

Database Application Components

Data Entry Forms

• A primary means to enter data into a database and to edit existing data.
• Can also be used to query (Query By Example).
• Data are typically arranged in groups of related data items. Consider the tables we created from last week:
  CUSTOMERS
  Customer_Id, Name, Street, City, State, Zip
  

  ACCOUNTS
  Customer_Id, Account_Number, Account_Type, Date_Opened, Balance
  

  A data entry form would have fields that correspond to each of the database columns. For example, a Customer data entry form would have fields for:
  Customer_Id, Name, Street, City, State, Zip
  

• With Graphical User Interfaces, more efficient data entry can be affected.
  GIGO
  • List boxes - provide a list of valid values for a user to choose from. Example: List of US States.
  • Radio Buttons - Exclusive list of options. Example: Gender M/F
  • Check Boxes - Non-Exclusive list of options.

• Other options to constrain user input:
  • Convert input to all upper case or all lowercase
  • Restrict the number of digits entered
  • Check for valid numbers and other values

• A typical database application will have roughly one form for each table.
• Also information-only forms (Query-only). Not used for updating or creating new data.

Queries

• Common Queries to the database can be formed by the database designers.
• Save queries for specific purposes.
• User supplies criteria for the query and executes the query against the tables in the database.

Reports

• Primarily used to convey large portions of data in the database.
• Output can be specially formatted for a variety of purposes such as printing mailing labels.

Applications Code

• Applications code is used to enforce business rules.
• For example:
  No account should have a negative balance

  Applications Code:
  

       IF (withdraw_amount > current_balance) THEN
          DISPLAY_ERROR("Insufficient Funds")
       ELSE
          SET current_balance = current_balance - withdraw_amount
       

Menus

• Menus tie applications together.
• Provide a convenient way for users to access forms, reports and queries.

WWW Applications

• Users access database through a WWW Browser.
• Data entry forms can be filled out and submitted to be saved in the database.
• Reports can be formatted and displayed as web pages.
• Menus are simply links to different web pages for for forms and reports.
• Caveat: All applications Code typically resides on the WWW server.
• MS Access '97 has tools to support:
  • Exporting a report as an HTML page
  • Creating Microsoft Active Server Pages (ASP) for data entry forms.
• An example of a typical WWW data entry form tied to a back end database:

For Next Week

• Check for formal assignments
• Chapters to Read
  Connolly, Begg, Holowczak Chapters 6, 7 and 9
• Form your groups and converge on one or two ideas for the group project.