Berdasarkan diskusi dalam obrolan untuk 3 pengelompokan, dan ini menyediakan SQLFiddle untuk data uji (tidak banyak data di sana).
Karena menguji data dengan jendela geser di mana now()
dalam kaitannya dengan data itu, variabel berikut digunakan untuk "membekukan" now()
. Hanya untuk memfasilitasi pengujian dan verifikasi keluaran.
Jadi, abaikan itu dan ubah 4 referensi dalam kode yang menggunakannya (perhatikan bahwa Grup 3 menggunakannya dua kali).
now()
variabel:
select @theNow:=now();
-- REM OUT the following line. It is used only for testing (as now will chg, your data won't)
select @theNow:='2016-06-23 14:00:00';
Permintaan:
select id,sentNum,message,sentTime,startAtTime,sentByTime,msgType,theGrp from
( select id,sentNum,message,sentTime,startAtTime,sentByTime,msgType,theGrp,
if([email protected],greatest(@sentNumChg:=1,0),least(@sentNumChg:=0,1)) as dummy1,
if([email protected],greatest(@grpChg:=1,0),least(@grpChg:=0,1)) as dummy2,
if(@sentNumChg=1 or @grpChg=1,@seqNum:=1,@seqNum:[email protected]+1) as seqNum,
@lastSentNum:=sentNum as setLast01,
@lastGrp:=theGrp as setLast02
from
( -- GROUP 1: sentByTime<=now(), INVITE
select `id`, `sentNum`, `message`, `sentTime`, `startAtTime`, `sentByTime`, `msgType`, 1 as theGrp
from SmsQueue
where sentByTime<[email protected] and msgType='invite'
UNION ALL
-- GROUP 2 startAtTime<=now(), BROADCAST
select `id`, `sentNum`, `message`, `sentTime`, `startAtTime`, `sentByTime`, `msgType`, 2 as theGrp
from SmsQueue
where startAtTime<[email protected] and msgType='broadcast'
UNION ALL
-- GROUP 3: sentByTime>now() && startAtTime<=now(), INVITE
select `id`, `sentNum`, `message`, `sentTime`, `startAtTime`, `sentByTime`, `msgType`, 3 as theGrp
from SmsQueue
where sentByTime>@theNow and startAtTime<[email protected] and msgType='invite'
) d1
cross join (select @sentNumChg:=0,@grpChg:=0,@lastSentNum:='',@lastGrp:=0,@seqNum:=0) as xParams
order by sentNum,theGrp,sentByTime,id -- id is the tie-break
) d2
where (theGrp=1 and seqNum<3) or (theGrp=2 and seqNum=1) or (theGrp=3 and seqNum=1)
order by sentNum,theGrp;
Output (alat klien saya saat ini sedang ditantang teks):
Lihat komentar umum saya di bagian atas ini jawaban saya untuk penggunaan variabel tingkat lanjut.