Programming with VB6

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Nov 5, 2013 (3 years and 7 months ago)

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Basics of Database
Programming with VB6

By: Mr. Carl Michael L. Morados

Presentor: Mr. Carl Michael L. Morados

What is a database?


Database



a collection of related data or
information, that is stored, modified and
transmitted.

Student Database

Personal Info

Grades

Payments

Presentor: Mr. Carl Michael L. Morados

Structure of a Database


Tables



collection of related information


Records


single piece of information


Fields



smallest unit of information that is
useful to users.

Presentor: Mr. Carl Michael L. Morados

Structure of a Database

Student Information Sheet

Name:

Address:

Contact No.:

Table

Record

Fields

Presentor: Mr. Carl Michael L. Morados

Visual Basic and Database


Front End



the user interface, which the
program uses to interact with the user.


Back End



the database, where all data
coming from the user are saved, to be
retrieved later.

Presentor: Mr. Carl Michael L. Morados

Visual Basic and Database

The user interacts with

the program by user

interface or screens.

(Visual Basic)

ADO Object

Database Driver

(Database Application)

Presentor: Mr. Carl Michael L. Morados

What are database drivers?


It allows different programming languages to
communicate or get information from different
data sources.

Presentor: Mr. Carl Michael L. Morados

Using the ADODC Object


ADODC (ActiveX Data Object)



an object
used to connect a Visual Basic program to a
database.

ADODC Object on the

toolbox

ADODC Object when

placed on the form

Presentor: Mr. Carl Michael L. Morados

Inserting the ADODC Object

1.
Go to
Project

menu, then choose
Components
. (or right click on the toolbox)

2.
When the components dialog appears,
choose
Microsoft ADO Data Control 6.0
.

Presentor: Mr. Carl Michael L. Morados

Inserting the ADODC Object

Components Dialog Window

Presentor: Mr. Carl Michael L. Morados

Connecting the ADODC to a
database


Straight Connection


Setting of the Database Provider and directly
specifying the path of the database (location).


Using ODBC (Open Database
Connectivity)


Creating a Data Source Name (DSN) using the
ODBC Administrator of Windows

Presentor: Mr. Carl Michael L. Morados

Steps in Connecting ADODC


Right Click on the ADO Object


Connect the ADO by using the Connection
String or ODBC Data Sources

Presentor: Mr. Carl Michael L. Morados

Steps in Connecting ADODC

Choose the correct
database

provider.

Presentor: Mr. Carl Michael L. Morados

Steps in Connecting ADODC

Specify the correct path of

the database

Test the connection if the ADODC

where able to communicate with

the data source.

Presentor: Mr. Carl Michael L. Morados

Steps in Connecting ADODC

Specify how the ADODC will

connect to the table.

Presentor: Mr. Carl Michael L. Morados

Structure of an ADODC
commands

<adodc name>.RECORDSET.<method>

The Name of the adodc object

Refers to the table

object

Methods that can

be done to a table

Presentor: Mr. Carl Michael L. Morados

Types of ADODC methods


Record Operations


Addnew



used to add records to the table.


Delete



used to delete records from the table.


Update



used to save records to the table.


CancelUpdate



cancels any record
-
related
operations.


Presentor: Mr. Carl Michael L. Morados

Types of ADODC commands


Record Navigation


Find <parameters>

-

used to find or search
records, based on key fields.


Movefirst



go to the first record.


Movelast



go to the last record.


Movenext



go to the next record.


Moveprevious



go to the previous record.


Move(record no.)



go to a specified record no.

Presentor: Mr. Carl Michael L. Morados

Types of ADODC commands


Record Counters



RecordCount



returns the number of records on
the table


EOF



End of File, returns True if the record
pointer reaches the end of the table.


BOF



Beginning of File, returns True if the record
pointer reaches the beginning of the table

Presentor: Mr. Carl Michael L. Morados

Finding Records


FIND “[
key field
] like ‘
comparing value


e.g.


adoSTUD.RECORDSET.FIND “[LName] like ‘Locsin’”


In finding records, always REFRESH the table first. to
complete the code:


adoSTUD.REFRESH

adoSTUD.RECORDSET.FIND “[LName] like ‘Locsin’”



Presentor: Mr. Carl Michael L. Morados

Using the SQL Statements


SQL (Structured Query Language)



is
composed of series of statements and
clauses, which, when combined, perform
different actions.


Select Queries



returns a specific set of
records, based on criteria


Action Queries



performs actions such as
deleting, adding or updating records.

Presentor: Mr. Carl Michael L. Morados

Basic Structure of Select


SELECT <fields> FROM <tablename>
[<where> <condition> <order by>]


e.g.


Select * from StudInfo