OLE DB Provider and Visual Basic
This section helps you to integrate the PSQL OLE DB Provider into your Visual Basic development environment.
Non-Visual Programming
This procedure shows how to program in ADO and OLE DB without using the visual control objects.
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To program for OLE DB in Visual Basic:
1
Open a new project in VB 6
2
Click on the Project|References menu item to bring up the references dialog
3
Make sure that "Microsoft ActiveX Data Objects 2.1 Library" or "Microsoft ActiveX Data Objects 2.5 Library" is checked and press "OK"
4
Add three textboxes to the form
5
Bring up the code window and dimension and allocate a global recordset object using the following code (this should go in the General::Declarations code area):
Dim myData as New ADODB.Recordset
6
To have the recordset created on Form::Load, put the following code in the Form_Load event (we've set up DemoData as a DBNAMES entry, and we're going to use the Person file):
myData.CursorLocation = adUseServer
myData.Open "Person", "Provider=PervasiveOLEDB;Data Source=DemoData", adOpenDynamic, adLockOptimistic, adCmdTableDirect
7
We're going to want to display the records we find, so create the following subroutine:
Private Sub DisplayFields()
Text1 = myData.Fields(0)
Text2 = myData.Fields(1)
Text3 = myData.Fields(2)
End Sub
8
Add 4 buttons to the form, and add the following code:
Private Sub Command1_Click()
myData.MoveFirst
DisplayFields
End Sub
 
Private Sub Command2_Click()
myData.MovePrevious
DisplayFields
End Sub
 
Private Sub Command3_Click()
myData.MoveNext
DisplayFields
End Sub
 
Private Sub Command4_Click()
myData.MoveLast
DisplayFields
End Sub
9
To get the first record when the form loads, add the following as the last line in Form_Load:
Command1_Click
10
Run the application, and you will be able to use the buttons to navigate through the data. You may want to change the button captions and names to make things easier to see.
11
To add update capabilities, place another button on the form and give it the caption "Update" and the name "btnUpdate"
12
Add the following code so users cannot update the first field. Since the concurrency mode is adLockOptimistic, the update is applied automatically when the cursor moves off the current row. The update may also be used to force an update regardless of cursor position.
Private Sub btnUpdate_Click()
myData.Fields(1) = Text2
myData.Fields(2) = Text3
End Sub
Visual Programming
The PSQL provider has one property that is essential for initialization, and that is Data Source. OLE DB providers do not use DSN’s, so the Data Source property should be set to a DBNames value. For example, the connection string for an ADO Connection::Open command would be "Provider=PervasiveOLEDB;Data Source=<data store>", where <data store> is a DBName.
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To use the provider to fill a grid in Visual Basic:
1
Start Visual Basic 6
2
Begin a standard project
3
Click the Project | Components menu option to display the components dialog.
4
Select the checkboxes next to the following components and and click OK.
•
"Microsoft ADO Data Control 6.0 (OLEDB)"
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"Microsoft DataGrid Control 6.0 (OLEDB)"
5
Drag and drop one copy of each control onto the form.
6
Right click on the data control and select ADODC Properties from the pop-up menu
7
Click Build to bring up the connection string builder.
8
Select Pervasive OLE DB Provider from the list and click Next.
9
Enter a DBNames entry or a pathname for the Data Source
10
Click OK.
11
Click the RecordSource tab of the ADODC Properties dialog.
12
Change the command type to adCmdTable using the drop-down list.
13
Enter a table name or select one from the drop-down list and click OK.
14
Select the grid, and edit the properties using F4.
15
Change the Data Source property to adodc1 using the drop down list.
16
Run the application.