需求:
    给出如下条件进行批处理编排
    - 开始日期时间
    - 重复间隔(分钟)
    - 重复次数
    要求在档期内重复安排节目播出, 比如: 2003.01.01 08:00 开始每隔240分钟播出一次, 一共播出100次

    数据库表格(CO_SCHEDULE)
    ------------------------------
    N_PROGID        INT
    DT_STARTTIME    TIMESTAMP
    DT_ENDTIME        TIMESTAMP


存储过程的实现：

create table co_schedule(n_progid int,dt_starttime timestamp,dt_endtime timestamp);

//创建函数：
create function add_program_time(int4,timestamp,int4,int4,int4) returns bool as
declare
    prog_id alias for $1;
    duration_min alias for $3;
    period_min alias for $4;
    repeat_times alias for $5;
    i int;
    starttime timestamp;
    ins_starttime timestamp;
    ins_endtime timestamp;
begin
    starttime :=$2;
    i := 0;
    while i<repeat_times loop
        ins_starttime := starttime;
        ins_endtime := timestamp_pl_span(ins_starttime,duration_min || mins);
        starttime := timestamp_pl_span(ins_starttime,period_min || mins);
        insert into co_schedule values(prog_id,ins_starttime,ins_endtime);
        i := i+1;
    end loop;
    if i<repeat_times then
        return false;
    else
        return true;
    end if;
end;
language plpgsql;

//执行函数：
select add_program_time(1,2002-10-20 0:0:0,5,60,5);

//查看结果：select * from co_schedule;
n_progid |      dt_starttime      |       dt_endtime       
----------+------------------------+------------------------
        1 | 2002-10-20 00:00:00+08 | 2002-10-20 00:05:00+08
        1 | 2002-10-20 01:00:00+08 | 2002-10-20 01:05:00+08
        1 | 2002-10-20 02:00:00+08 | 2002-10-20 02:05:00+08
        1 | 2002-10-20 03:00:00+08 | 2002-10-20 03:05:00+08
        1 | 2002-10-20 04:00:00+08 | 2002-10-20 04:05:00+08

ps:
1.数据库一加载 plpgsql语言。如没有，
su - postgres
createlang plpgsql dbname
2.至于返回类型为bool,是因为我不知道如何让函数不返回值。等待改进。