มาปรึกษาความเป็นไปได้อีกแล้วครับ พอจะมีคำสั่ง ที่พอทำแบบนี้ได้บางไหมครับ

 conn.Open()
        cm = conn.CreateCommand()
        With cm
            .CommandText = "SELECT * FROM GoodsCheck "
            .CommandType = CommandType.Text
        End With
        da = New SqlDataAdapter(cm)
        da.Fill(dt2)
        conn.Close()

        DataGridView2.DataSource = dt2
        DataGridView2.Columns.Clear()

        Dim col As DataGridViewTextBoxColumn

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "goodsID"
            .HeaderText = "  รหัสครุภัณฑ์"
            .Width = "150"
        End With
        DataGridView2.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "room"
            .HeaderText = "  ห้อง"
            .Width = "150"
        End With
        DataGridView2.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "sumAmount"
            .HeaderText = "  จำนวน"
            .Width = "100"
        End With
        DataGridView2.Columns.Add(col)

        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "numSent"
            .HeaderText = "  จำนวนส่ง"
            .Width = "100"
        End With
        DataGridView2.Columns.Add(col)


        col = New DataGridViewTextBoxColumn()
        With col
            .DataPropertyName = "real"
            .HeaderText = "  จำนวนทั้งหมด"
            .Width = "150"
        End With
        DataGridView2.Columns.Add(col)

"SELECT goodsID,room,sumAmount,numSent,(sumAmount - numSent) as real FROM GoodsCheck "