获取最大值和最小值以及所有值和多个where子句

Question

I have this query which works very good

  SELECT cm.id ,cm.edited,cm.date_edited,cm.voteup,cm.votedown 
  FROM chat_messages cm 
  WHERE TIMESTAMPDIFF(SECOND,cm.date_edited,'$now') < 10 GROUP BY cm.id

Which gives me the entries which are edited in less then 10 seconds.

But along with that im trying to get also the max(voteup) and min(votedown)

But dont affect the first entries of the first query . How can i combine then to get all entries i need ?

Example:

if im getting 3 newly updates entries . i want to get them those 3 plus the max of voteup and votedown .

Example:

    id   edited  date_edited          voteup    votedown
    37      0      2016-03-05 22:13:03    5         0
    38      0      2016-04-02 11:15:00    3         7
    39      0      2016-03-05 22:10:06    10        6
    40      0      2016-03-20 21:40:06    5         0
    41      1      2016-04-20 22:28:59    5         0
    42      1      2016-03-20 21:59:15    0         20
    43      1      2016-04-21 22:20:25    8         0     <---- this new updated

My wished result is

    id   edited  date_edited         voteup  votedown  maxup  maxdown
    39      0      2016-03-05 22:10:06    10        6    10     NULL
    42      1      2016-03-20 21:59:15    0         20   NUll   20
    43      1      2016-04-21 22:20:25    8         0    NULL   NULL  

My $now time is 2016-04-21 22:20:20

explanation:

   -id 39 is having maxup vote i want get it

   -id 42  is having maxdown i want get it

   -id 43 is newly updated in that period of 10 seconds.

so i general i want get new updated entries pls the max up and down .

if many max voteup values are same then just choose one which have min votedown

Any solution to that pls ?

Here my sqlfiddle example

Edit: oh sorry i meant id . now wish my question is clear like

Answer 1

you will want to use a UNION statement:

SELECT * FROM (
    select cm.id ,cm.edited,cm.date_edited,cm.voteup,cm.votedown 
        , voteup as maxup, null AS maxdown
    from chat_messages cm
    ORDER BY voteup DESC, votedown
    LIMIT 1
) a
UNION
SELECT * FROM (
    select cm.id ,cm.edited,cm.date_edited,cm.voteup,cm.votedown 
        , null as maxup, votedown AS maxdown
    from chat_messages cm
    ORDER BY votedown DESC, voteup
    LIMIT 1
) b
UNION
SELECT * FROM (
  SELECT cm.id ,cm.edited,cm.date_edited,cm.voteup,cm.votedown 
        , null as maxup, null AS maxdown
  from chat_messages cm
  WHERE TIMESTAMPDIFF(SECOND,cm.date_edited,'2016-04-21 22:20:20') < 10
) c

note that I used '2016-04-21 22:20:20' , but you will want to substitute the $now back in

Answer 2

you can use user-defined variables to track your maximums and then outer query the rows that match your rules.

SELECT id,edited,date_edited,voteup,votedown,
       IF(voteup=@maxvoteup,voteup,NULL) as maxvoteup,
       IF(votedown=@maxvotedown,votedown,NULL) as maxvotedown
FROM (SELECT cm.id ,cm.edited,cm.date_edited,cm.voteup,cm.votedown,
       @maxvoteup := GREATEST(@maxvoteup,cm.voteup) as maxvoteup,
       @maxvotedown := GREATEST(@maxvotedown,cm.votedown) as maxvotedown
      FROM chat_messages cm,(SELECT @maxvoteup:=0,@maxvotedown:=0)initial
     )T
WHERE TIMESTAMPDIFF(SECOND,date_edited,'2016-04-21 22:20:25') < 10
   OR voteup = @maxvoteup
   OR votedown = @maxvotedown
ORDER BY id ASC

sqlfiddle

Here's another query that is much more CRAZY..but it works ..

for maxupvote row, it'll find row that has maxupvote and minimum down vote, if more than 1 row exists (in a tie) it'll grab the row with latest/largest id. for maxdownvote row, it'll find row that has maxdownvote and minimum up vote, if more than 1 row exists (in a tie) it'll grab the row with latest/largest id.

SELECT id,edited,date_edited,voteup,votedown,
       IF(voteup=@maxvoteup,voteup,NULL) as maxvoteup,
       IF(votedown=@maxvotedown,votedown,NULL) as maxvotedown
FROM (SELECT cm.id ,cm.edited,cm.date_edited,cm.voteup,cm.votedown,
       @minvotedown :=
            (CASE WHEN cm.voteup > @maxvoteup OR (cm.voteup = @maxvoteup AND cm.votedown < @minvotedown)
                  THEN cm.votedown
                  ELSE @minvotedown
            END),
       @minvoteup :=
            (CASE WHEN cm.votedown > @maxvotedown OR (cm.votedown = @maxvotedown AND cm.voteup < @minvoteup)
                  THEN cm.voteup
                  ELSE @minvoteup
            END),
       @maxvoteup := GREATEST(@maxvoteup,cm.voteup) as maxvoteup,
       @maxvotedown := GREATEST(@maxvotedown,cm.votedown) as maxvotedown,
       @maxvoteupid :=
             (CASE WHEN cm.voteup = @maxvoteup AND cm.votedown = @minvotedown 
              THEN cm.id
              ELSE @maxvoteupid
              END),
       @maxvotedownid :=
             (CASE WHEN cm.votedown = @maxvotedown AND cm.voteup = @minvoteup
              THEN cm.id
              ELSE @maxvotedownid
              END)
      FROM chat_messages cm,(SELECT @maxvoteup:=0,@maxvotedown:=0,@minvoteup:=0,@minvotedown:=0,@maxvoteupid:=0,@maxvotedownid:=0)initial
      ORDER BY cm.id ASC
     )T
WHERE TIMESTAMPDIFF(SECOND,date_edited,'2016-04-21 22:20:25') < 10
   OR id = @maxvoteupid
   OR id = @maxvotedownid
ORDER BY id ASC;

sqlfiddle

I call it CRAZY because it is...if i was doing this. I would just run 3 separate queries

1 query to return one row with order by upvote DESC, downvote ASC, id DESC limit 1

1 query to return one row with order by downvote DESC, upvote ASC, id DESC limit 1

1 query to return one row that's within the last 10 seconds order by id DESC this way it's much easier to maintain.