using Devart.Data.Oracle;
...
class Program
{
    void PrintDept(OracleConnection connection)
    {
        OracleCommand command = connection.CreateCommand();
        command.CommandText = "select * from dept";
        
        // Call the Close method when you are finished using the OracleDataReader 
        // to use the associated OracleConnection for any other purpose.
        // Or put the reader in the using block to call Close implicitly.
        using (OracleDataReader reader = command.ExecuteReader())
        {
            // printing the column names
            for (int i = 0; i < reader.FieldCount; i++)
                Console.Write(reader.GetName(i).ToString() + "\t");
            Console.Write(Environment.NewLine);
            // Always call Read before accesing data
            while (reader.Read())
            {
                // printing the table content
                for (int i = 0; i < reader.FieldCount; i++)
                    Console.Write(reader.GetValue(i).ToString() + "\t");
                Console.Write(Environment.NewLine);
            }
        }
    }
    
    void ModifyDept(OracleConnection connection)
    {
        OracleCommand command = connection.CreateCommand();
        command.CommandText = "UPDATE DEPT SET LOC='VEGAS' WHERE DEPTNO > 20";
        
        // return value of ExecuteNonQuery (i) is the number of rows affected by the command
        int i = command.ExecuteNonQuery();
        Console.WriteLine(Environment.NewLine + "Rows in DEPT updated: {0}", i + Environment.NewLine);
    }
    
    static void Main(string[] args)
    {
        using (OracleConnection conn 
            = new OracleConnection("User Id=Scott;Password=tiger;Data Source=Ora;"))
        {
            try
            {
                conn.Open();
                Program program = new Program();
                
                // printing out the Dept table to console
                program.PrintDept(conn);
                
                // updating records in Dept
                program.ModifyDept(conn);
                
                // printing out the Dept table to console
                program.PrintDept(conn);
            }
            catch (OracleException ex)
            {
                Console.WriteLine("Exception occurs: {0}", ex.Message);
            }
            finally
            {
                Console.ReadLine();
            }
        }
    }
}

public void UseDataTable()
{
   OracleDataTable myDataTable 
    = new OracleDataTable("SELECT * FROM Dept", "User Id=Scott;Password=tiger;Data Source=Ora;");
   try
   {
       // FetchAll=true means to retrieve data from server entirely when DataTable is opened.
       //  By default, FetchAll is set to false - only minimal quantity of rows is requested at once,
       //  which leads to better initial response time and less network traffic.
       myDataTable.FetchAll = true;
     
       // populating DataTable with data from data source
       myDataTable.Active = true;
     
       // modifying the third record
       myDataTable.Rows[3]["DName"] = "Researches";
     
       // Update method executes the appropriate commands (delete, insert, or update) in the data source.
       Console.WriteLine(myDataTable.Update() + " rows updated.");
       
       // printing the DataTable content
       foreach (DataRow myRow in myDataTable.Rows)
       {
          foreach (DataColumn myCol in myDataTable.Columns)
          {
              Console.Write(myRow[myCol] + "\t");
          }
          Console.WriteLine();
       }
     }
     finally
     {
        //Active=false does not clear the data, but frees the resources allocated on the server, if any.
        myDataTable.Active = false;
     }
}