SQL - Converting 24-hour (“military”) time (2145) to “AM/PM time” (9:45 pm)

Question

I have 2 fields I\'m working with that are stored as smallint military structured times.
Edit I\'m running on IBM Informix Dynamic Server Version 10.00.FC9

Answer 1

LONG-hand approach... but works

select  substr((mtg_rec.beg_tm-1200),0,1)||":"||substr((mtg_rec.beg_tm-1200),2,2)||" pm" beg_tm,
            substr((mtg_rec.end_tm-1200),0,1)||":"||substr((mtg_rec.end_tm-1200),2,2)||" pm" end_tm
    from    mtg_rec
    where   mtg_rec.beg_tm between 1300 and 2159
            and mtg_rec.end_tm between 1300 and 2159
    union
    select  substr((mtg_rec.beg_tm-1200),0,1)||":"||substr((mtg_rec.beg_tm-1200),2,2)||" pm" beg_tm,
            substr((mtg_rec.end_tm-1200),0,2)||":"||substr((mtg_rec.end_tm-1200),3,2)||" pm" end_tm
    from    mtg_rec
    where   mtg_rec.beg_tm between 1300 and 2159
            and mtg_rec.end_tm between 2159 and 2400
    union
    select  substr((mtg_rec.beg_tm-1200),0,2)||":"||substr((mtg_rec.beg_tm-1200),3,2)||" pm" beg_tm,
            substr((mtg_rec.end_tm-1200),0,2)||":"||substr((mtg_rec.end_tm-1200),3,2)||" pm" end_tm
            mtg_rec.days
    from    mtg_rec
    where   mtg_rec.beg_tm between 2159 and 2400
            and mtg_rec.end_tm between 2159 and 2400
    union
     select substr((mtg_rec.beg_tm),0,1)||":"||(substr((mtg_rec.beg_tm),2,2))||" am" beg_tm,
            substr((mtg_rec.end_tm),0,1)||":"||(substr((mtg_rec.end_tm),2,2))||" am" end_tm
            mtg_rec.days
    from    mtg_rec
    where   mtg_rec.beg_tm between 0 and 959
            and mtg_rec.end_tm between 0 and 959
    union
     select substr((mtg_rec.beg_tm),0,2)||":"||(substr((mtg_rec.beg_tm),3,2))||" am" beg_tm,
            substr((mtg_rec.end_tm),0,2)||":"||(substr((mtg_rec.end_tm),3,2))||" am" end_tm
            mtg_rec.days
    from    mtg_rec
    where   mtg_rec.beg_tm between 1000 and 1259
            and mtg_rec.end_tm between 1000 and 1259
    union
     select cast(beg_tm as varchar(4)),
            cast(end_tm as varchar(4))
    from    mtg_rec
    where   mtg_rec.beg_tm = 0
            and mtg_rec.end_tm = 0
    into temp time_machine with no log;