Logic error using foreach data column and data rows in datatable to insert into sql server

foreach (DataColumn dc in dt.Columns) {
        if (dc.ColumnName.ToString() == "Oracle" || dc.ColumnName.ToString() == "F1") {
        } else {
                foreach (DataRow dr in dt.Rows) {
                        insertStatement = insertStatement + "INSERT INTO Allocation (OracleCostCenter, OracleGL, Allocation, FiscalYear, Addedby) VALUES ('"
                                                                    + dr["Oracle"].ToString().Trim() + "','" + dc.ColumnName.ToString() + "','" + dr[dc.ColumnName.ToString()]
                                                                    + "'," + DropDownList1.SelectedValue + ",'" + addedby1.Text + "')\n";
                        SqlCommand sqlCommand = new SqlCommand(insertStatement, conn);
                        sqlCommand.ExecuteNonQuery();
                }
        }
}

first sorry for the indentation of my codes....

next is my question. i try the above code... the total amount of data insert to my sql server is abt 10,000 plus datas... i have try in a counter into the foreach loop, and the counter after the end of the 2 foreach loops is 612... so how come my sql server has 10k plus datas being inserted?? it is supposed to have only 612 datas...