Visual Studio 2008 Multiselection querry with LINQ Query

With Visual Studio 2008 and SQL Server 2005 I have a Form where i drag the data Class (tbl_Name ) Linked to a Table Named tbl_Name

The Table has 5 Column : NameID/Name/Town/Country/Continent

So the Form show a Grid representing the tbl_Name with the 5 column
I have in same form Toolstrip 2 combo box named as follow :

ToolStripComboBox1 It Populate Taking Data from the column Continent
ToolStripComboBox2 It Populate Taking Data from the collumn Country

In the Form I have also a Button : Button3 that i use to trigger the filter action

I am using the following code to filter the Grid by Continent and by Country and it works very well

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

Dim MultyQuerry = From tbl_Name In db.tbl_Names _
Where tbl_Name.Continent = Me.ToolStripComboBox1.SelectedItem.ToString _
And tbl_Name.Country = Me.ToolStripComboBox2.SelectedItem.ToString _
Select tbl_Name
Me.Tbl_NameBindingSource.DataSource = MultyQuerry
End Sub

Now let me come to my Problem

All is working if i have both Combo Box with a value :

But it give me error if one of the comboBox is empty

Is anyone helping me to change my code so to handle the Null value ???

Thanks

Programming TheoryMicrosoft ApplicationsVisual Basic.NET

Last Comment

sanlorenzo

8/22/2022 - Mon

ASKER CERTIFIED SOLUTION

Nasir Razzaq

10/1/2012

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sanlorenzo

10/1/2012

ASKER

here is teh code i develop , do you see any Problem , i try in any possible combination and it works
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click

If Me.ToolStripComboBox1.SelectedItem > "" And Me.ToolStripComboBox2.SelectedItem > "" Then

Dim MultyQuerry = From tbl_Name In db.tbl_Names _
Where tbl_Name.Continent = Me.ToolStripComboBox1.SelectedItem.ToString _
And tbl_Name.Country = Me.ToolStripComboBox2.SelectedItem.ToString _
Select tbl_Name
Me.Tbl_NameBindingSource.DataSource = MultyQuerry

End If
If Me.ToolStripComboBox1.SelectedItem > "" And Me.ToolStripComboBox2.SelectedItem = "" Then

Dim MultyQuerry1 = From tbl_Name In db.tbl_Names _
Where tbl_Name.Continent = Me.ToolStripComboBox1.SelectedItem.ToString _
Select tbl_Name

Me.Tbl_NameBindingSource.DataSource = MultyQuerry1
End If
If Me.ToolStripComboBox1.SelectedItem = "" And Me.ToolStripComboBox2.SelectedItem > "" Then

Dim MultyQuerry2 = From tbl_Name In db.tbl_Names _
Where tbl_Name.Country = Me.ToolStripComboBox2.SelectedItem.ToString _
Select tbl_Name
Me.Tbl_NameBindingSource.DataSource = MultyQuerry2
End If
If Me.ToolStripComboBox1.SelectedItem = "" And Me.ToolStripComboBox2.SelectedItem = "" Then

Dim MultyQuerry3 = From tbl_Name In db.tbl_Names

Select Case db.tbl_Names

End Select

Me.Tbl_NameBindingSource.DataSource = MultyQuerry3

End If

End Sub

sanlorenzo

12/5/2013

ASKER

Is there any one to help , if for instance the Combo Box instead being 2 become 4 , i see i should have a better code to apply ???

Thanks

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