CSCI 220 Programming With Visual Basic
Lecture 13- The Data Access Control

Overview of Data Access
  Allows programmer to build database with 3rd party
  program
  Allows for large, complex databases
  Encourages use of relational (multi-table) databases
  Makes Index management simple
  Can read several different kinds of databases
  Requires little code for simplest incarnation
  
Creating a database
  Use a database management system such as:
     DBase, Foxpro, Access
     Create data format, enter starting data if preferred
     Define tables, fields, and indices
     Save the database
  Use the data manager program to create an Access database
     DATAMGR.EXE in VB directory
     Allows development and rudimentary editing of ACCESS
     format databases
     Create Database
     Create Table (start with 1)
     Define fields
     Define Indices
     Close Data manager
     
The Data Control
  Select the data control from the toolbar and draw it on
  your form
  Set the DatabaseName property to whatever you called your
  database
  If you used a format other than ACCESS, use the connect
  property to indicate which type
  Set the recordsource property to the table you wish to
  access
  
Bound controls:
  The following controls can be bound to a database:
     Text boxes, Picture boxes, Images, Labels, and Check
     boxes
  Draw an appropriate control on the form
  Set the DataSource property to the name of the Data
  Control (Data1)
  Set the DataField property to the field you wish the
  object to reflect
  When running, changes to this field will automatically be
  reflected in the database
  Database changes will also be reflected in this field
  automatically.
  
Creating a new record
  Create a command button with the following code:
     Data1.Recordset.AddNew
     
Moving around the database
  VCR - like control buttons are already attached to the
  Data control.
Language
  The RecordSet object
  Handy commands
     Move commands
     Find Commands
     Searching
     SQL
  Using on - line help
  
Program design considerations:
  Getting help
     Use the Search command on help menu or...
     Type a keyword, place the cursor on that word, and
     press F1 key
     Don't be afraid to experiment.
  Steps for designing a program
     Define the program in English:  What will it do?
     Sketch out a design for the program's main form(s)
     Determine what controls will be used to solve the
     problem.
     Write (in English) what will happen when the user
     activates key controls
     Translate those directions into more precise pseudocode
     Translate pseudocode into Code
     Test and Debug
     
     
Debugging
  Run your program
  Try different input methods
  Try to mess it up
Errors will happen
Tracing crashes
  Look at what was happening on screen when program crashed
  Try to anticipate what code was operating.
  Guess what went wrong.
  look carefully at error message
  Press F1 for help if you don't understand
  look at where cursor is when you are returned to code.
  Note that computer sets point where it NOTICED error,
  NOT necessarily where error OCCURRED
Bugs
  Program doesn't crash outright, but still doesn't perform
  as you expected
  Follow same technique as for crashes
  Print values of appropriate control variables to screen,
  temp labels
  Use of DEBUG window
  Debug menu Watch etc.