asp.net中用DataReader高效率分页

/// <summary>
/// PageList for DataReader
/// </summary>
/// <param name="connectionString"></param>
/// <param name="sql"></param>
/// <param name="pageSize"></param>
/// <param name="curPage"></param>
/// <param name="pageCount"></param>
/// <param name="count"></param>
/// <param name="cmdParms"></param>
/// <returns></returns>
public DataTable PageListReader(string connectionString, string sql, int pageSize, int curPage, out int pageCount, out int count, params DbParameter[] cmdParms)
{
int first = 0;
int last = 0;
int fieldCount = 0;
using (SqlConnection conn = new SqlConnection(connectionString))
{
SqlCommand cmd = conn.CreateCommand();
PrepareCommand(cmd, conn, null, CommandType.Text, sql, cmdParms);
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
DataTable dt = new DataTable();
fieldCount = reader.FieldCount;
for (int i = 0; i < fieldCount; i++)
{
DataColumn col = new DataColumn();
col.ColumnName = reader.GetName(i);
col.DataType = reader.GetFieldType(i);
dt.Columns.Add(col);
}
count = 0;
first = (curPage - 1) * pageSize+1;
last = curPage * pageSize;
while (reader.Read())
{
count++;
if (count >= first && last >= count)
{
DataRow r = dt.NewRow();
for (int i = 0; i < fieldCount; i++)
{
r[i] = reader[i];
}
dt.Rows.Add(r);
}
}
reader.Close();
pageCount = Convert.ToInt32(Math.Ceiling((double)count / (double)pageSize));
return dt;
}
}

/// <summary>
/// 分页获取数据(Sql Server 2005) for ROW_NUMBER()
/// </summary>
/// <param name="connectionString">数据库链接</param>
/// <param name="sql">获取数据集的Sql</param>
/// <param name="fldSort">排序字段,可以多个</param>
/// <param name="pageSize">每页显示多少条</param>
/// <param name="curPage">当前页码</param>
/// <param name="pageCount">总页数</param>
/// <param name="count">总记录数</param>
///<param name="cmdParms">DbParameter</param>
/// <returns>DataTable</returns>
public DataTable PageList(string connectionString, string sql, string fldSort, int pageSize, int curPage, out int pageCount, out int count, params DbParameter[] cmdParms)
{
StringBuilder strSql = new StringBuilder();
strSql.AppendFormat(@"SELECT count(0) from {0} as MyTableCount;
select * from (
SELECT ROW_NUMBER() OVER(order by {1}) RowNumber,*
from {0} mytable
) mytable2
where RowNumber between {2} and {3}"
, sql, fldSort, Convert.ToString((curPage - 1) * pageSize + 1), Convert.ToString((curPage * pageSize)));
DataSet ds = ExecuteQuery(connectionString, CommandType.Text, strSql.ToString(), cmdParms);
count = Convert.ToInt32(ds.Tables[0].Rows[0][0]);
pageCount = Convert.ToInt32(Math.Ceiling((double)count / (double)pageSize));
return ds.Tables[1];
}