在Oracle 11g中未使用C＃导入空值

Question

I am currently creating an application to import data from DataGridView into Oracle 11g. My problem is if for example the column REPORTING_OUTBOUND_DATE is empty then I get error message System.FormatException: "The string was not recognized as valid DateTime". How can I fix these errors and AM IMPORTANT at all ? Is there any way to program everything better? Thank you

private void Btn_SAVE_IN_DATABASE_VEUPEN_Click(object sender, EventArgs e)
    {
        for (int i = 0; i < dataGridView2.Rows.Count - 1; i++) //Schleife für INSERT Befehl
        {

            OracleConnection con = new OracleConnection("Data Source=(***********************");
            con.Open();

            string sql = "INSERT INTO AFTERSALES.INPUT_BOARDLEVEL_REPAIR_VEUPEN (BLR_REPORT_DATE, MONTH_OF_REPAIR_END, PCB_COUNTER, MANUFACTURER, REPORTING_OUTBOUND_DATE,  EMPTY,  QTY)"
                       + "VALUES (:BLR_REPORT_DATE, :MONTH_OF_REPAIR_END, :PCB_COUNTER, :MANUFACTURER, :REPORTING_OUTBOUND_DATE, :EMPTY, :QTY)";

            OracleCommand cmd = new OracleCommand(sql, con);
            //cmd.CommandText = sql;
            cmd.Parameters.Add(":BLR_REPORT_DATE", Convert.ToDateTime(dataGridView2.Rows[i].Cells[0].Value).ToString("dd.MM.yyyy"));
            cmd.Parameters.Add(":MONTH_OF_REPAIR_END", dataGridView2.Rows[i].Cells[1].Value);
            cmd.Parameters.Add(":PCB_COUNTER", dataGridView2.Rows[i].Cells[2].Value);
            cmd.Parameters.Add(":MANUFACTURER", dataGridView2.Rows[i].Cells[3].Value);
            cmd.Parameters.Add(":REPORTING_OUTBOUND_DATE", Convert.ToDateTime(dataGridView2.Rows[i].Cells[4].Value).ToString("dd.MM.yyyy"));
            cmd.Parameters.Add(":EMPTY", dataGridView2.Rows[i].Cells[5].Value);
            cmd.Parameters.Add(":QTY", dataGridView2.Rows[i].Cells[6].Value);       
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }

Answer 1

Try checking for null before converting. Something like this:

dataGridView2.Rows[i].Cells[0].Value == null? null : Convert.ToDateTime(dataGridView2.Rows[i].Cells[0].Value).ToString("dd.MM.yyyy")