using Oracle.ManagedDataAccess.Client; //引入命名空間

  private void button1_Click(object sender, EventArgs e)
  {
   string strSql = "select * from s_user";
   DataTable dt = QueryDt(strSql);
  }
//Oracle連接字符串
private static string strconn = "Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=172.30.0.37)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=EMES)));Persist Security Info=True;User ID=EMES_DEV;Password=EMES_DEV;";

  private DataTable QueryDt(string sql)
  {
   using (OracleConnection conn = new OracleConnection(strconn))
   {
    try
    {
     if (conn.State != ConnectionState.Open)
     {
      conn.Open();
     }
     OracleDataAdapter adap = new OracleDataAdapter(sql, conn);
     DataTable dt = new DataTable();
     adap.Fill(dt);
     return dt;
    }
    catch (Exception ex)
    {
     return null;
    }
    finally
    {
     conn.Close();
    }
   }
  }

格式:
string strconn = "Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=172.30.0.37)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=EMES)));Persist Security Info=True;User ID=EMES_DEV;Password=EMES_DEV;";

格式:
string strconn = "Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=遠(yuǎn)程服務(wù)器IP地址)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=遠(yuǎn)程服務(wù)器數(shù)據(jù)庫服務(wù)名稱)));Persist Security Info=True;User ID=數(shù)據(jù)庫用戶名;Password=數(shù)據(jù)庫密碼;";