Operator '=' is not defined for type 'DBNull' and type 'Boolean'.??/

Question

I am going to count the checked and unchecked check box in my attendance but that come out in my code."Operator '=' is not defined for type 'DBNull' and type 'Boolean'.??"... pls help..your help is greatly appreciated. thanks

my code:

    Dim Present As Integer = 0
    Dim Absent As Integer = 0
    For a = 0 To Table2___lieDataGridView.RowCount - 1
        For b = 0 To Table2___lieDataGridView.ColumnCount - 8
            If Table2___lieDataGridView.Rows(a).Cells(b + 5).Value = True Then

                Present += 1
            Else
                Absent += 1
            End If
        Next
        Table2___lieDataGridView.Rows(a).Cells(10).Value = Present
        Table2___lieDataGridView.Rows(a).Cells(11).Value = Absent
        Present = 0
        Absent = 0


    Next

You need to check if value is Nothing or DBNull and if it is not then you can safely cast it to a Boolean and then make the comparison. — Alex Wiese
See my answer below. You can use the built-in IsDBNull function — Alex Wiese

Alex Wiese Alex Wiese · Accepted Answer · 2014-09-26T04:06:45

You need to use the IsDBNull function to check for a null value before making the comparison.

If Not IsDBNull(Table2___lieDataGridView.Rows(a).Cells(b + 5).Value) AndAlso Table2___lieDataGridView.Rows(a).Cells(b + 5).Value Then
End If

Operator '=' is not defined for type 'DBNull' and type 'Boolean'.??/

2 Answers