未使用对象实例设置的对象变量

Question

Just because (in my code) some times looks the sqlDataReader to be open and tells me that "there is already an open data reader"
I decide to put this line: If Not SqlReader.IsClosed Then SqlReader.Close()

Select Case PreviousRecord
    Case True
        SqlComm = New SqlCommand("Select * from " & tmpName & " where FuelOrderValid = '" & True & "' Order by FuelLoadDate", ReportsSQLConn)
    Case False
        SqlComm = New SqlCommand("Select * from " & tmpName & " where FuelOrderValid = '" & True & "' And FuelOrderID = '" & ordNum & "' Order by FuelLoadDate", ReportsSQLConn)
End Select      

If Not SqlReader.IsClosed Then SqlReader.Close()

If SqlComm.Connection.State = Data.ConnectionState.Open Then
    SqlReader = SqlComm.ExecuteReader(CommandBehavior.KeyInfo)
Else
    SqlComm.Connection.Open()
    SqlReader = SqlComm.ExecuteReader(CommandBehavior.KeyInfo)
End If

But now, when it comes to execute the instruction
If Not SqlReader.IsClosed Then SqlReader.Close()
It gives the error:
Object Variable Not Set To An Instance Of An Object
I really can't understand why is doing this.
Please is there anybody to assist me?

Answer 1

The SqlReader has not been initialised before calling SqlReader.IsClosed and SqlReader.Close . You can check whether its nothing like this:

If SqlReader IsNot Nothing Then
    ' Do something with the SqlReader'
Else
    ' Create a new SqlReader'
End If