mysql - A more efficient way to do this select and update loop -


this table votes.

"id"    "votedelm"  "votetype"  "voteprocessed" "country" "3"     "6"         "1"         "0"             "us"//1-1=0  "4"     "8"         "0"         "0"             "us"//2+0-1=1 "9"     "8"         "1"         "0"             "us"  "5"     "9"         "0"         "0"             "us"//2+0-1=1 "10"    "9"         "1"         "0"             "us"

and table likes

  "id"      "type"  "parent"    "country"   "votes"     6       10      3                    1     8       10      7                    2     9       10      7                    2

i update table likes doing in event:

//pseudocode - inside mysql scheduled event //select votes select id, votedelm, votetype, country votes if votetype = 0  update likes set votes=votes+1 id=votedelm , country=country update votes set voteprocessed = 1 id = id  elseif votetype = 1  update likes set votes=votes-1 id=votedelm , country=country update votes set voteprocessed = 1 id = id  end if

this whole things takes 1 row @ time. see better , more efficient way sql here?

heres event:

begin      declare vid int(10) default '0';      declare velm int(10) default '0';     declare vtype tinyint(1) default '0';     declare vprocessed tinyint(1) default '0';     declare vcountry varchar(2) default "";     declare updatedone int default false;      -- declare cursor employee email     declare updater cursor         select id, votedelm, votetype, voteprocessed, country votes;      -- declare not found handler     declare continue handler          not found set updatedone = true;      open updater;      doupdate: loop          fetch updater vid, velm, vtype, vprocessed, vcountry;          if updatedone             leave doupdate;         end if;          -- update likes         update likes                 inner join votes                     on votes.velm = likes.id , votes.vcountry = likes.country                     set                     likes.votes = if(votes.vtype = 0,likes.votes+1,likes.votes-1),                     votes.vid = 1;      end loop doupdate;      close updater;  end

you can try this:

update     likes inner join votes     on votes.votedelm = likes.id     , votes.country = likes.country set     likes.votes = if(votes.vote_type = 0,likes.votes+1,likes.votes-1),     votes.voteprocessed = 1     votes.voteprocessed = 0

you can read more multiple updates here


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