how can i save 2textbox in one field in sql using c#

cmd,Parameters.Add("@VisitoEmail", SqlDbType.NVarchar).Value = txtvisitormail.Text,Trim() + " | " +  txtoptionalmail.Text,Trim(); // you use , instead | symbol or you can try below thread by adding one more table for email with using forignkey

 https://stackoverflow.com/questions/24865310/how-to-store-multiple-values-in-single-field-in-sql-database