ORACLE 计算时间区间

buffer.append(" with date_info as(");
buffer.append(" select to_date('"+param.get("BEGIN_TIME")+"','yyyy-mm-dd') as start_date,");
buffer.append(" to_date('"+param.get("END_TIME")+"','yyyy-mm-dd')-to_date('"+param.get("BEGIN_TIME")+"','yyyy-mm-dd')+1 as dt");
buffer.append(" from dual),");
buffer.append(" date_group as(");
buffer.append(" select start_date+(level-1) as start_date,");
buffer.append(" start_date+level as end_date");
buffer.append(" from date_info connect by level<=date_info.dt");
buffer.append(" ),");