SIngle Insert or Update statement - ADO.Net

In VB6 using MDAC 2.8 I could do a single select statement that would act as either an Insert or an update. Is there a way to do this in ADO.net?
My old VB6 code
Dim dbData As New ADODB.Connection
Dim rs1 As New ADODB.Recordset
Dim strParm As String
Dim strCusNo As String
'
strParm = "Provider=SQLOLEDB; Data Source=SQL2000; Initial Catalog=DATA_01; User ID=UserName; Password=password"
dbData.Open strParm
'
strParm = "Select CusNo from CusFil Where CusNo = '" & strCusNo & "'"
rs1.Open strParm, dbData, adOpenStatic, adLockOptimistic, adCmdText
If rs1.BOF And rs1.EOF Then
    rs1.AddNew
Else

End If
With rs1
    !CusNo = strCusNo
    .Update
End With
rs1.Close
'
Set rs1 = Nothing
dbData.Close
Set dbData = Nothing

Is there an ADO.Net equivalent?

thanks,
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