Dictionary and condition - asp.net

Question

I have been working on an assignment in which I have to upload some records from a file to Dictionary and manipulate.
Actually file have number of record with same invoice number and different tax values and I have to add all those values and make it only one invoice
what I'm trying to do
I'm passing values from a foreach loop to a function which check if the dictionary is empty so it will simply add first record and on second call it will check weather any record in dictionary have same invoice number so it will sum and update current tax value to one already added,
what I'm getting
when I pass 2nd value (and so on) the previous value of last entry in dictionary some how update itself with current value before even comparing which I don't want.
public jd_records jd = new jd_records();
Dictionary<int, jd_records> jdValues = new Dictionary<int, jd_records>();
//Calling values with loop while jd is a publicly declared object of class jd_records
foreach (DataRow dr in jddt.Rows)
{
//jd_records jdPass = new jd_records();
jd.supplierName = dr["Supplier"].ToString();
jd.supplierNTN = dr["Supplier NTN"].ToString();
jd.invoiceNo = dr["JDE Invoice Number"].ToString();
jd.invoiceDate = DateTime.Parse(dr["JDE Invoice Date"].ToString());
if (dr["Taxable Amount"].ToString().Equals(""))
{ jd.taxable = 0; }
else
{ jd.taxable = float.Parse(dr["Taxable Amount"].ToString()); }
if (dr["Tax To Pay"].ToString().Equals(""))
{ jd.tax = 0; }
else
{ jd.tax = float.Parse(dr["Tax To Pay"].ToString()); }
jdRecordCheck();
}
called function
public void jdRecordCheck()
{
if (jdValues.Count < 1)
{
jdValues.Add(0, jd);
}
else //previous record values (at key 0) changes to new jd value when come to this else part on execution
{
foreach (KeyValuePair<int,jd_records> jdVal in jdValues)
{
if ((jdVal.Value.supplierNTN.Equals(jd.supplierNTN)) && (jdVal.Value.invoiceNo.Equals(jd.invoiceNo)))
{
jdVal.Value.tax = jdVal.Value.tax + jd.tax;
jdVal.Value.taxable = jdVal.Value.taxable + jd.taxable;
jdValues[jdVal.Key] = jdVal.Value;
}
else
{
jdValues.Add(jdVal.Key + 1, jd);
}
}
}
}
I'll be very thankful if anyone helps.

Answer 1

Seems to me this would be much easier to do with Linq, which contains functions for grouping and summing.
List<jd_records> result = jddt.Rows
.GroupBy(jd => jd.invoiceNo)
.Select(jd => new jd_records
{
invoiceNo = jd.invoiceNo,
totalTax = jd.Sum(d => d.tax)
}).ToList();