C # Connection database is written in SqlHelper

Static class SqlHelper {private static string connstr = configurationmanager.connectionstrings["Dbconstr"].        ConnectionString; The principle of encapsulation method: Put the invariant in the method change in the parameter list public static int ExecuteNonQuery (String sql, params sqlparameter[] Parameters ) {using (SqlConnection coon = new SqlConnection (connstr)) {coon.                Open (); using (SqlCommand cmd = coon.                    CreateCommand ()) {cmd.commandtext = SQL; Cmd.                    Parameters.addrange (Parameters); return CMD.                ExecuteNonQuery ();            }}} public static object ExecuteScalar (String sql, params sqlparameter[] parameters) { using (SqlConnection coon = new SqlConnection (connstr)) {coon.                Open (); using (SqlCommand cmd = coon.                    CreateCommand ()) {cmd.commandtext = SQL; Cmd. ParaMeters.                    AddRange (parameters); return CMD.                ExecuteScalar (); }}}//Because the query is relatively small, you can directly use the table public static DataTable executedatatable (String sql            , params sqlparameter[] parameters) {using (SqlConnection coon = new SqlConnection (CONNSTR)) {Coon.                Open (); using (SqlCommand cmd = coon.                    CreateCommand ()) {cmd.commandtext = SQL; Cmd.                    Parameters.addrange (Parameters);                    DataSet DataSet = new DataSet ();                    SqlDataAdapter adapter = new SqlDataAdapter (cmd); Adapter.                    Fill (DataSet); return DataSet.                Tables[0]; }            }        }

C # Connection database is written in SqlHelper