Strucking with the following code

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C#

Hi,

I am using the following code to check the common message Ids of 3 excel sheets columns

i = 2;
foreach (DataRow row in lstDS[2].Tables[0].Rows)
{


    string fieldFromDB = row[1].ToString();
    string FromDB = row[2].ToString();

    foreach (DataRow row1 in lstDS[0].Tables[0].Rows)
    {
        string fieldFromDB1 = row1[1].ToString();

        if (fieldFromDB == fieldFromDB1)
        {

            foreach (DataRow row2 in lstDS[1].Tables[0].Rows)
            {
                string fieldFromDB2 = row2[1].ToString();

                if (fieldFromDB1 == fieldFromDB2)
                {
                    //commonMsgId = fieldFromDB;

                    xlWorkSheet4.Cells[i, 1] = row[1];
                    xlWorkSheet4.Cells[i, 2] = row[13];
                    xlWorkSheet4.Cells[i, 3] = row1[13];
                    xlWorkSheet4.Cells[i, 4] = row2[13];
                    xlWorkSheet4.Cells[i, 5] = 10.ToString();
                    i++;

                }



            }
        }
    }
}

This code is working fine

Now I need to check the columns of 2 excel sheets for the common message Id and from those I need to eliminate common message Id of 3 excel sheet columns

I am trying something like this in the following code, but this includes the common message Ids of the 3 excel sheets also

i = 2;
foreach (DataRow row in lstDS[2].Tables[0].Rows)
{


    string fieldFromDB = row[1].ToString();
    string FromDB = row[2].ToString();

    foreach (DataRow row1 in lstDS[0].Tables[0].Rows)
    {
        string fieldFromDB1 = row1[1].ToString();

        if (fieldFromDB == fieldFromDB1)
        {

           //do something
        }

    }
}

How can I exclude the common message Ids of 3 excel sheets from this code snippet

Thanks
John