strange output in using sql update query in c#.net

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C#

MS-Access

Hello everyone,
I have to change the data in one of the fields in my table in access.
I use the update query.
but the query only deleting the old data from the table and not entering the new data with the foll code.
code:

String esql = string.Format("update company_list SET company_name ='{0}' where company_name ='{1}'", edited_name, selected_name);
OleDbCommand myupdate = new OleDbCommand(esql, con);
myupdate = new OleDbCommand(esql, con);
myupdate.ExecuteNonQuery();

so, I try to change the code, but here, it says that @new_name must have a default value.
but how to set a default value

code:

using (OleDbCommand myupdate = con.CreateCommand())
             {
 myupdate.CommandText = "update company_list set company_name = @new_name where company_name = @old_name";
                 
                 myupdate.Parameters.AddWithValue("@new_name",edited_name);
                 myupdate.Parameters.AddWithValue("@old_name", selected_name);
                 
                 myupdate.ExecuteNonQuery();
}

Please help asap.