DATASET 与 DATAREADER对象有什么区别

/// <param name="paras">参数列表，没有参数填入null</param>
/// <returns>返回的首行首列</returns>
public static object GetObject(string strSQL, OracleParameter[] paras, CommandType cmdtype)
{
object o = null;
using (OracleConnection conn = new OracleConnection(strConn))
{
OracleCommand cmd = new OracleCommand(strSQL, conn);
cmd.CommandType = cmdtype;
if (paras != null)
{
cmd.Parameters.AddRange(paras);
}
conn.Open();
o = cmd.ExecuteScalar();
conn.Close();
}
return o;
}
#endregion
#region 查询获取DataReader------------------------------------
/// <summary>
/// 调用不带参数的存储过程，返回DataReader对象
/// </summary>
/// <param name="procName">存储过程名称</param>
/// <returns>DataReader对象</returns>
public static OracleDataReader GetReaderByProc(string procName)
{
return GetReaderByProc(procName, null);
}
/// <summary>
/// 调用带有参数的存储过程，返回DataReader对象
/// </summary>
/// <param name="procName">存储过程名</param>
/// <param name="paras">参数数组</param>
/// <returns>DataReader对象</returns>
public static OracleDataReader GetReaderByProc(string procName, OracleParameter[] paras)
{
return GetReader(procName, paras, CommandType.StoredProcedure);
}
/// <summary>
/// 根据sql语句返回DataReader对象
/// </summary>
/// <param name="strSQL">sql语句</param>
/// <returns>DataReader对象</returns>
public static OracleDataReader GetReader(string strSQL)
{
return GetReader(strSQL, null);
}
/// <summary>
/// 根据sql语句和参数返回DataReader对象
/// </summary>
/// <param name="strSQL">sql语句</param>
/// <param name="paras">参数数组</param>
/// <returns>DataReader对象</returns>
public static OracleDataReader GetReader(string strSQL, OracleParameter[] paras)
{
return GetReader(strSQL, paras, CommandType.Text);
}
/// <summary>
/// 查询SQL语句获取DataReader
/// </summary>
/// <param name="strSQL">查询的SQL语句</param>
/// <param name="paras">参数列表，没有参数填入null</param>
/// <returns>查询到的DataReader（关闭该对象的时候，自动关闭连接）</returns>
public static OracleDataReader GetReader(string strSQL, OracleParameter[] paras, CommandType cmdtype)
{
OracleDataReader sqldr = null;
OracleConnection conn = new OracleConnection(strConn);
OracleCommand cmd = new OracleCommand(strSQL, conn);
cmd.CommandType = cmdtype;
if (paras != null)
{
cmd.Parameters.AddRange(paras);
}
conn.Open();