Input string was not in a correct format. C# SQL

Question

I am putting SQL values inside <td> and this line below it's causing a format error, i don't know if the parsing is incorrect or missing something. Please help

litAccordionFooter.Text += "<td style='width: 12.2%;font-weight: bold;'>" 
    + string.Format("{0:C}", (((ds.Tables[1].Rows[0]["TOTAL_AMT"]))
    == DBNull.Value ? 1 
        : decimal.Parse((ds.Tables[1].Rows[0]["TOTAL_AMT"]).ToString())) 
        / ((int.Parse((ds.Tables[1].Rows[0]["TOTAL_QTY"]).ToString())) == 0 
            || ds.Tables[1].Rows[0]["TOTAL_QTY"] == DBNull.Value ? 1 
                : (int.Parse((ds.Tables[1].Rows[0]["TOTAL_QTY"]).ToString())))) + "</td>";

Answer 1

As @JoãoKleberson says, you should validate they are not null or empty and that they have actually a int and decimal representation

int     total_Amt = default(int);
decimal total_Qty = default(decimal);

if (decimal.TryParse(ds.Tables[1].Rows[0]["TOTAL_AMT"].ToString(), out total_Qty) &&
        int.TryParse(ds.Tables[1].Rows[0]["TOTAL_QTY"].ToString(), out total_Amt))
{
    var myString = "<td style='width: 12.2%;font-weight:bold;'>" +
    string.Format("{0:C}", total_Amt / total_Qty == 0 ? 1 : total_Qty) + "</td>";
}
else
{
    // The TOTAL_AMT and/or TOTAL_QTY values are not valid to convert them, 
    // verify they are not null and that they have the correct format
}

This way you can safety try to convert the values to the desired type, if the can't be converted the flow is going to be to the else clause

Answer 2

Make sure this statement:

(ds.Tables [1] .Rows [0] ["TOTAL_AMT"])
(ds.Tables [1] .Rows [0] ["TOTAL_QTY"])

It is not null or empty