VB 6 Database Programming

1
VB 6 Database Programming

• Chapter 1

2
Database Concepts

• Relational Databases
• Sample Databases
• Biblio.mdb
• Nwind.mdb
• Normalization
• Access and VB

3
USER INTERFACE (VB PROGRAM)
DATABASE ENGINE (JET DLLS)
DATASTORE (Biblio.mdb)
4
User Interface

• What the User Sees!
• Forms to display and modify data
• Modules and Classes
• VB Code to add, delete and modify records
• Queries to retrieve information
• Create reports and graphs
• Send commands to the database engine

5
The Database Engine

• Software program that manages the information in
  the database
• Jet - Access database engine
• Native to VB and Access
• Interface between VB and data (Brains of the
  operation)
• Group of DLL (dynamic link library) files
• Automatically linked to VB program at run time
• Handles reading and writing to data store

6
The Database Engine contd

• Jet contd
• Performs housekeeping tasks
• Indexing the tables, security, locking, and more
• Query Processor (SQL requests)
• Self contained (no additional software required
  to run application)

7
The Datastore

• Physical files containing the database tables
• Access
• Spreadsheets
• Paradox
• Oracle

8
Data ControlsDAO vs ADO

• DAO (Data Access Objects)
• Has been the most widespread method of data
  access
• Established and Solid methodology
• ADO (ActiveX Data Objects)
• Successor to DAO
• Fewer objects
• More properties, methods and events
• Does not support all of DAOs functionality

9
Why use DAO?

• Modifying an existing DAO Application
• Small desktop application
• Application running on a local server
• ADO does not support users, groups and so on
• Database security
• Access uses Jet and DAO

10
Why use ADO?

• Deploying data over the internet
• Easier to use than DAO
• More powerful and permits easy access to more
  data sources
• Standard data access object model across
  Microsoft tools (starting with VB 6.0)

11
Summary

• When you have learned DAO, moving to ADO is simple