doubt in sqlconnectiomn

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C#

ADO.NET

hi to all,

private double function()
    {
        //double d2 = a;
        
            SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["stockforecasting"].ConnectionString);
            con.Open();
            double d1 = 0, sum = 0;
            SqlDataAdapter adp = new SqlDataAdapter("select eps,pbya,normalisation from stock where pricedate between '" + txtstartdate.Text + "' AND '" + txtenddate.Text + "'", con);
            DataSet ds = new DataSet();
            adp.Fill(ds, "stock");
            if (ds.Tables["stock"].Rows.Count - 1 > 0)
            {
                for (int i = 0; i < ds.Tables["stock"].Rows.Count; i++)
                {
                    double eps = 0, pbya = 0, normalise = 0,a1=0;
                    for (int j = 0; j < 3; j++)
                    {
                        double d3 = 0;

                        string str = ds.Tables["stock"].Rows[i][j].ToString();
                        d1 = Convert.ToDouble(str);
                        if (j == 0)
                        {
                            Random rnd = new Random();
                            double value = rnd.NextDouble();
                            a1 = value;
                            d3 = d1 * value;
                            eps = d1;
                            SqlCommand cnd = new SqlCommand("insert into stock3(startdate,enddate,eps,weight) values('" + txtstartdate.Text + "','" + txtenddate.Text + "','" + d1 + "','" + value + "')", con);
                            cnd.ExecuteNonQuery();
                            //Console.WriteLine(eps);
                            //Console.WriteLine(value);

                        }
                        else if (j == 1)
                        {
                            Random rnd = new Random();
                            double value1 = rnd.NextDouble();
                            d3 = d1 * value1;
                            pbya = d1;
                            SqlCommand cnd = new SqlCommand("update stock3 set pbya='" + d1 + "',weight1='" + value1 + "' where weight='" + a1 + "' ", con);
                            cnd.ExecuteNonQuery();
                            //Console.WriteLine(pbya);
                            //Console.WriteLine(value1);

                        }
                        else if (j == 2)
                        {
                            Random rnd = new Random();
                            double value2 = rnd.NextDouble();
                            d3 = d1 * value2;
                            normalise = d1;
                            SqlCommand cnd = new SqlCommand("update stock3 set normalise='" + d1 + "',weight2='" + value2 + "' where weight='" + a1 + "' ", con);
                            cnd.ExecuteNonQuery();
                            //Console.WriteLine(normalise);
                            //Console.WriteLine(value2);

                        }

                        sum = sum + d3;
                        
                    }
                }
            }
            con.Close();
            //adp.Dispose();
            //ds.Reset();
            return sum;
                
    }

here is my code. i called this function 3 times. its working. but if i put the breakpoint , the regular loop works. if i remove the breakpoints,it generates same random values. i dont know wat to do