MIS 300 Management Information Systems

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MIS 300 Management Information Systems

• Computer Programming
• (continued from Software Overview)

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Creating SoftwareComputer Programming

• Tell the computer exactly what you want it to do
  and how to do it
• A very detailed business process model
• Flow chart the logic of the business process to
  be programmed
• The computer does what you tell it to do!

3
From Source Code to Executable Program
Source code
Executable Program
Source code
Source code
Linker
Compiler
Libraries
Object Code
4
Bugs

• What are bugs? Why bugs?
• Why does software have bugs?
• Syntax bug versus a logic bug?
• How can bugs be reduced?
• Testing, testing, testing
• Debugging utilities
• 125M Mars Orbiter lost metric conversion
  problem
• Was Y2K a bug?

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Object code, user doc

• What is difference between object code and source
  code?
• Example width03out.c, width03out.obj
• What is a compiler?
• Why is source code nice to have?
• Can you always get source code?
• Do you always get user documentation when you buy
  software or an information system?

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They Write the Right StuffWriting Bug Free Code

• Software for space shuttle Lockheed Martin,
  Inc.
• CMM5 for on-board shuttle group
• How does their process support their mission?
• What is the culture like? What are the people
  like?
• How does their organizational structure support
  their mission?
• Comparison to typical software development?

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Access Macros

• Simple, powerful automation
• Respond to events with actions
• events usually user initiated such as?
• execute a sequence of tasks
• Can create relatively complex applications using
  Macros with little or no VBA code
• Some things can only be done with VBA
• Lets explore FineFood.mdb and Tutorial 9

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Recording Macros in Excel

• Useful for learning VBA
• Really useful for learning details of object
  model
• A way to start a program
• To use
• start recorder (Tools-Macro-Record New Macro)
• do stuff
• stop recorder (Push the stop button)
• go look/edit code in VBE
• Cant record logic
• Lets look at some examples in Recording.xls

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Where does code live in Access and Excel (and
Word, etc)?

• Code behind forms
• Code related to controls on forms
• Respond to events (e.g. button click)
• Code Modules
• General subroutines and functions
• Not specific to a form
• Visual Basic Editor for both

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Structured Programming Concepts

• Divide code into independent procedures
• Each with its own purpose
• Procedures related hierarchically
• They talk through a list of arguments or
  parameters
• Logic
• sequence
• selection
• iteration

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Main Program and SubroutinesDivide programs into
independent proceduresTalk via passed
parameters
Filename
Main Program
Results
Values
Results
Values
Read data file
Output results
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3
1
Do calculations
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Variables

• Temporary storage of values (recall from
  algebra?)
• Can do things like
• xx1
• AvgCost TotalCost/NumItems
• Declare variables with Dim
• pick data type for the variable
• Example Dim NumItems As Integer

Variable type
Variable name
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Some Data Types

• String for text like Bob Smith
• Integer integers in 32768 to 32768
• Long for bigger integers
• Boolean only True (-1) or False (0)
• Double numbers with decimals
• Currency monetary values
• Date for dates and times
• Object specific versions for each object type
• Variant let VBA decide how to deal with

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Control Logic Condition or Selection If Then
Else End If
Example syntax from Visual Basic
If some condition Then a bunch of statements
to be done if the condition is True Else a
bunch of statements to be done if the condition
is False End If
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Control Logic Looping or Iteration ForNext,
Do WhileLoop
For counter start To stop bunch of
statements to be repeated Next counter
Example syntax from Visual Basic
Do While some condition bunch of statements
to be repeated Loop
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The Averaging Program

• Ive written an Excel VBA program to
• Let user enter a series of numbers, one at a time
  into a simple data input form
• When the user is done entering numbers, calculate
  the average of the numbers entered
• Display the calculated average to the user
• Lets find use of
• Variables
• Sequence
• Selection
• Iteration

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Major OO Programming Concept 1Classes and
Objects
Object Oriented
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Microsoft Access Object Model TableDefs A
collection of tables
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The Object Model a car analogy
We have object called Car
Each Car is part of the collection Cars
Each Car has properties that describe it such as
make, model, color, price, age, purpose, etc.
Each Car has methods that control it such as
accelerate, stop, turn left, turn right,, etc.
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Object Model for Cars

• Hierarchical
• Collections are plural
• Each object has its own specific set of
  properties and methods

Cars (Car)
Wheels (Wheel)
Horn
Hood
HoodOrnament
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Working with Objects in VBA

• Properties and Methods
• Appearance and behavior control
• SomeObject.SomeProperty
• SomeObject.SomeMethod method arguments
• Collections of Objects
• the Collection itself is an object

(adjective)
(noun)
(verb)
(adverbs)
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Accessing specific objects in collections and
down hierarchy

• By index number
• By name
• Down hierarchy
• Worksheets(BreakEvenModel).Range(FCost).Value

Lets look at BreakEven.xls
Worksheets(1)
Worksheets(BreakEvenModel)
Dots separate objects in hierarchy
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Major OO Programming Concept 2Inheritance and
Methods
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Major OO Programming Concept 3Messages and
Polymorphism (?!)
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Object Property Values

• Car Object is a template for creating specific
  car instances (inheritance)
• Each car can have its own set of values for each
  property

NOT a real program!
Set property values
Use Drive method (send message)
Check a property value and use a method if value
meets condition
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Simple Communication with User

• MsgBox show user message, get button click
  response
• InputBox get a single value from the user

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Some programming style tips

• Use meaningful variable names
• Indent
• Use lots of comments
• Create End If, Loop, End With, Next right after
  you create If, Do While, With, For so you dont
  forget
• Use white space

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Programming with VBA

• Figure out what you logically want to accomplish
• Flow chart and/or pseudo-code
• Figure out which objects you need to
  create/modify/access.
• Figure out how to use those objects properties
  and methods to do what you want to do.
• Hunting through help, common sense, object
  browser, record a macro

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Visual Basic Editor

• Project Explorer
• Code Modules
• Immediate Window
• Object Browser
• Locals
• Watch

• Run, continue, reset
• Single step into, over out
• Breaking out
• Using Breakpoints
• Auto List Members
• Auto Quick Info

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The Averaging ProgramRevisited

• Ive written an Excel VBA program to
• Let user enter a series of numbers, one at a time
  into a simple data input form
• When the user is done entering numbers, calculate
  the average of the numbers entered
• Display the calculated average to the user
• Well explore in Access (Program2000.mdb)
• More about the Visual Basic Editor
• Lets figure out how the code works
• Make some program enhancements