Code
<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
  </configSections>
  <connectionStrings>
    <add name="FileOracle" connectionString="Data Source=File;Persist Security Info=True;User ID=Fileuser;Password=123"
      providerName="System.Data.OracleClient" />
  </connectionStrings>
  <appSettings>
    <add key="FileDB" value="FileOracle" />
    <add key="FileConnString" value="Data Source=File;Persist Security Info=True;User ID=Fileuser;Password=123" />
  </appSettings>
</configuration>

Code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Data;
using System.Data.Common;
using System.Data.OracleClient;
using System.Configuration;


namespace FileManager.Ocl
{
    public class DBCL
    {
        private string _DBName;

        public DBCL()
        {
            //
            // 
            //
        }

        public string DBName
        {
            get { return _DBName; }
            set { _DBName = value; }
        }


        /// <summary>
        /// 获取 DataSet
        /// </summary>
        public DataSet GetDS(string SQL)
        {
            string strConnection = DBName;
            OracleConnection oraConn = new OracleConnection(strConnection);

            OracleDataAdapter oda = new OracleDataAdapter(SQL, oraConn);
            DataSet ds = new DataSet();
            
            try
            {
                oda.Fill(ds);
            }
            catch(Exception ee)
            {
                throw ee;

            }
            return ds;
        }
    }
}

Code

using FileManager.Ocl;
using System.Configuration;


private void bt_Debug_Click(object sender, EventArgs e)
{
    dbcl = new DBCL();

    DataSet ds = new DataSet();

    int intCountRows = 0;
    int intCountColumns = 0;

    dbcl.DBName = ConfigurationSettings.AppSettings["FileConnString"];

    string sql = "select * from FileInformation";


    ds = dbcl.GetDS(sql);    
    intCountRows = ds.Tables[0].Rows.Count;

    for (int i = 0; i < intCountRows; i++)
    {
        this.tb_debug.Text += ds.Tables[0].Rows[i]["File_Name"].ToString() + "\r\n";//tb_debug=TextBox
        
    }

}