如何使用Oracle数据库的RowID,RowNum进行数据分页读取

对于Oracle数据库，可以直接采用SQL语句的形式，查询出每页的记录
方案一：
/// <summary>
/// 生成分页SQL
/// </summary>
/// <param name="_sqlStr">查询的SQL，支持多表关联，排序等</param>
/// <param name="_sortStr"></param>
/// <param name="_startNum">开始行</param>
/// <param name="_pageSize">记录数</param>
/// <returns></returns>
private string BuildPagerSQL(string _sqlStr, int _startNum, int _pageSize)
{
    string sqlStr = _sqlStr;
    _sqlStr = _sqlStr.Insert(7, " ROWNUM R , ");
    sqlStr = "SELECT * FROM ( ";
    sqlStr += _sqlStr  + " ) T1 , ( ";
    sqlStr += " SELECT R FROM ( SELECT R , ROWNUM C FROM ( ";
    sqlStr += _sqlStr + " ) ) WHERE C > " + _startNum
    + " AND C <= " + (_startNum + _pageSize) + " ) T2 WHERE T1.R = T2.R";
    return sqlStr;
}

方案二：
private string BuildPagerSQL(string sqlStr , int StartNum , int PageSize)
{
    int endNum = StartNum + PageSize;
    string _sqlStr = @"select B.* from ( select A.* , RowNum rn from
                         ( " + sqlStr + " ) A where RowNum < '" + endNum + "' ) B where rn > '" + StartNum + "'";
    return _sqlStr;
}