关于用c#怎样连接oracle的问题

尝试连上Oracle，并用OracleCommand命令读取数据库中的记录，显示在控制台上：

 1using System;
 2using System.Data;
 3using System.Data.OracleClient;
 4
 5public class MainClass
 6{
 7    static void Main()
 8    {
 9        OracleConnection conn = new OracleConnection();
10        conn.StateChange += new StateChangeEventHandler(OnStateChanged);
11        conn.ConnectionString = "Data Source = chenchong; User Id = system; Password = ;";
12        try
13        {
14            conn.Open();
15            Console.WriteLine("打开数据库连接成功。");
16            OracleCommand command = new OracleCommand();
17//            command.CommandText = "";
18            command.CommandText = "select nsrmc from scott.nsr where nsrmc like :pNsrmc order by nsrmc";
19            command.Connection = conn;
20            OracleParameter parameter = command.Parameters.Add("pNsrmc", OracleType.VarChar);
21            parameter.Value = "_国%";
22            OracleDataReader reader = command.ExecuteReader();
23
24            // 以下验证是否可以同时打开两个DataReader
25            OracleCommand command2 = new OracleCommand();
26            command2.CommandText = "select Count(*) from scott.nsr";
27            command2.Connection = conn;
28            OracleDataReader reader2 = command2.ExecuteReader();
29            reader2.Read();
30            Console.WriteLine("数据库共有 {0} 个记录。", reader2.GetInt32(0));
31            reader2.Close();
32
33            while (reader.Read())
34            {
35                if (!reader.IsDBNull(reader.GetOrdinal("Nsrmc")))
36                {
37                    Console.WriteLine(reader.GetString(reader.GetOrdinal("Nsrmc")).Trim());
38                }
39//                string s = null;
40//                Console.WriteLine(s);
41            }
42            command.CommandText = "select count(nsrmc) from scott.nsr where nsrmc like :pNsrmc order by nsrmc";
43            Console.WriteLine("符合条件的共有 {0} 个记录。",command.ExecuteScalar());
44        }
45        catch (Exception e)
46        {
47            Console.WriteLine("出现了异常：{0}", e.ToString());
48        }
49        finally
50        {
51            if (conn != null)
52            {
53                conn.Close();
54            }
55        }
56
57        Console.ReadLine();
58    }
59
60    private static void OnStateChanged(object sender, StateChangeEventArgs e)
61    {
62        Console.WriteLine("数据库连接的状态发生改变，原状态为：{0}，当前状态为：{1}。", e.OriginalState, e.CurrentState);
63    }
64}