遍歷開始日期到結(jié)束日期的每一天，若有查詢某段日期下有什么業(yè)務(wù)或者事件發(fā)生時，可用到此函數(shù)。
    create or replace type class_date as object
    (
    year varchar2(10),
    month varchar2(10),
    day varchar2(20)
    )--定義所需要的日期類
    -----------------------------------------------------------------------------
    create or replace type table_date is table of class_date--日期類返回table類型
    ------------------------------------------------------------------------------
    create or replace function minusDay(firstDay in varchar2,lastDay in varchar2)
    return table_date pipelined
    as
    firstYear number;
    firstMonth number;
    lastYear number;
    lastMonth number;
    totalDay number;
    totalMonth number;
    currentDay varchar2(40);
    currentYear varchar2(40);
    type tt is record(
    day varchar2(20),
    month varchar2(20),
    year varchar2(20)
    );
    v_date tt;
    begin
    --第一天的日期轉(zhuǎn)換
    select to_number(substr(firstDay,1,4))into firstYear from dual ;
    select to_number(substr(firstDay,6,2)) into firstMonth from dual;
    --第二天的日期轉(zhuǎn)換
    select to_number(substr(lastDay,1,4)) into lastYear from dual;
    select to_number(substr(lastDay,6,2)) into lastMonth from dual;
    --1 第一個日期早于第二個日期
    if to_number(to_date(firstDay,'yyyy-mm-dd')-to_date(lastDay,'yyyy-mm-dd')) <0 then
    dbms_output.put_line('第一個日期早于第二個日期！');
    end if;
    --2 第一個日期晚于第二個日期
    --------相同年份
    if firstYear = lastYear then
    v_date.year := to_char(firstYear);
    --------相同月份
    if firstMonth = lastMonth then
    v_date.month := to_char(firstMonth);
    -- 天數(shù)差
    totalDay := to_number(to_date(lastDay,'yyyy-mm-dd')-to_date(firstDay,'yyyy-mm-dd'));
    if totalDay = 0 then
    v_date.day := firstDay;
    pipe row(class_date(v_date.year,v_date.month,v_date.day));
    elsif totalDay >0 then
    for dayId in to_number(substr(firstDay,9,2))..to_number(substr(lastDay,9,2)) loop
    v_date.day :=to_char(substr(firstDay,1,7)||'-'||to_char(dayId)) ;
    pipe row(class_date(v_date.year,v_date.month,v_date.day));
    dbms_output.put_line( v_date.day);
    end loop;
    end if;
    --------不同月份
    elsif firstMonth < lastMonth then
    ---月份差
    --totalMonth := lastMonth - firstMonth;
    for id in firstMonth..lastMonth-1 loop
    v_date.month := to_char(id);
    --滿月天數(shù)差
    totalDay := to_number(last_day(to_date(firstYear||'-'||to_char(id)||'-'||'01','yyyy-mm-dd'))-to_date(firstYear||'-'||to_char(id)||'-'||'01','yyyy-mm-dd'))+1;
    for dayId in 1..totalDay loop
    v_date.day := substr(firstDay,1,7)||'-'||to_char(dayId) ;
    pipe row(class_date(v_date.year,v_date.month,v_date.day));
    dbms_output.put_line( v_date.day);
    end loop;
    end loop;
    --最后一個月的遍歷
    v_date.month := to_char(lastMonth);
    -- totalDay :=to_date(lastMonth,'yyyy-mm-dd') -to_date(to_char(lastYear)||'-'||to_char(lastMonth)||'-01','yyyy-mm-dd');
    totalDay := to_number(to_date(lastDay,'yyyy-mm-dd')-to_date(substr(lastDay,1,7)||'-01','yyyy-mm-dd'))+1;
    for id in 1..totalDay loop
    v_date.day := substr(lastDay,1,7)||'-'||to_char(id);
    pipe row(class_date(v_date.year,v_date.month,v_date.day));
    dbms_output.put_line( v_date.day);
    end loop;
    end if;
    --------不同年份
    elsif firstYear < lastYear then
    ----------------------------------------------
    --第一個月
    v_date.year := to_char(firstYear);
    v_date.month := substr(firstDay,6,2);
    totalDay :=to_number(substr( to_char(last_day(to_date(firstDay,'yyyy-mm-dd')),'yyyy-mm-dd'),9,2));
    for dayId in to_number(substr(firstDay,9,2)) ..totalDay loop
    v_date.day := to_char(dayId);
    pipe row(class_date(v_date.year,v_date.month,v_date.day));
    end loop;
    ---------------------------------------------------------------
    --中間所有月數(shù)的日期添加
    totalMonth := to_number( months_between(to_date(lastDay,'yyyy-mm-dd'),to_date(firstDay,'yyyy-mm-dd')))-1;
    currentDay := firstDay;
    currentDay := substr(currentDay,1,8)||'01';
    for monthId in 1..totalMonth loop
    --月數(shù)循環(huán)
    currentDay:=
    to_char(add_months(to_date(currentDay,'yyyy-mm-dd'),1),'yyyy-mm-dd') ;
    currentYear := substr(currentDay,1,4);
    v_date.year := to_char(substr(trim(currentDay),1,4));
    v_date.month := to_char(substr(trim(currentDay),6,2));
    --天數(shù)循環(huán)
    totalDay := to_number(last_day(to_date(currentDay,'yyyy-mm-dd'))-to_date(currentYear||'-'||substr(currentDay,6,2)||'-01','yyyy-mm-dd'))+1;
    for dayId in 1 .. totalDay loop
    v_date.day := to_char(dayId);
    pipe row(class_date(v_date.year,v_date.month,v_date.day));
    dbms_output.put_line( v_date.day);
    end loop;
    end loop;
    -----------------------------------------------------------------------------------
    --最后一個月
    totalDay := to_number(substr(lastDay,9,2));
    v_date.month := to_number(substr(lastDay,6,2));
    for dayId in 1 .. totalDay loop
    v_date.day := to_char(dayId);
    pipe row(class_date(v_date.year,v_date.month,v_date.day));
    end loop;
    end if;
    end minusDay;