postgresql - Simplify and/or optimize sql query with INTERSECT or HAVING -

-

i have following data:

 tag_id | taggable_id  --------+-------------       1 |           1       2 |           1       3 |           1       4 |           1       1 |           2       2 |           2       5 |           2       6 |           2       7 |           3       8 |           3       9 |           3      10 |           3

and want bring taggable_ids in group of tag_ids , in group , another... (max 4 groups).
example:

  • if search taggable_ids tag_id 1 or 7 , tag_id 4 should return 1
  • if search taggable_ids tag_id 1 , tag_id 6 , tag_id 2 or 8 should return 2
  • if search taggable_ids tag_id 8 , tag_id 5 should not return ids

in gross way(for second example), query following:

select taggable_id taggings tag_id in (1) intersect select taggable_id taggings tag_id in (6) intersect select taggable_id taggings tag_id in (2,8)

i think simplifying it, looks like:

select taggable_id taggings tag_id in (1,2,6,8) group taggable_id having count(*)=3

but i'm wondering if can done in simpler way. thoughts?

this can cast case of relational division. have assembled arsenal of query techniques under related question:

depending on data distribution , other factors, may fastest:

select distinct taggable_id   taggings t1 join   taggings t2 using (taggable_id) join   taggings t3 using (taggable_id)  t1.tag_id = 1 ,    t2.tag_id = 6 ,    t3.tag_id in (2, 8);

assuming unique (tag_id, taggable_id), distinct not needed example. might necessary other (list) predicates.

sql fiddle (building on @clodoaldo's, thanks).


Comments

Post a Comment

Popular posts from this blog

python - mat is not a numerical tuple : openCV error -

-
i have write down code showing error ma not getting it: please help: showing mat not numerical tuple: import cv import cv2 capture = cv2.videocapture("j.3gp") while(1): _, frame1 = capture.read() grayimage1 = cv2.cvtcolor(frame1, cv2.color_bgr2gray) _, frame2 = capture.read() grayimage2 = cv2.cvtcolor(frame2, cv2.color_bgr2gray) differenceimage = cv2.absdiff(grayimage1,grayimage2) thresholdimage = cv2.threshold(differenceimage,25,255,cv2.thresh_binary) cv2.imshow("difference image", differenceimage) cv2.imshow("threshold image", thresholdimage) cv2.imshow("image", frame1) k = cv2.waitkey(30) & 0xff error arising : ----------------------------------------------------------------------------------------- traceback (most recent call last): file "desk.py", line 15, in <module> cv2.imshow("threshold image", thresholdimage) typeerror: mat not numerical tuple ...
Read more

c# - MSAA finds controls UI Automation doesn't -

-
i'm working on automating windows application. i'm using teststack white framework. i've hit problem. program has 'window' object cannot see inside of. white shows no controls inside of it. inspect.exe shows no controls inside of either when running in ui automation mode. if switch inspect msaa see controls inside fine. there anyway me use msaa c# handle on these controls? if can identify msaa functions need, can use p/invoke call them c#. here's example article doing msaa: http://www.codeproject.com/articles/38906/ui-automation-using-microsoft-active-accessibility also, pinvoke.net can used identify iaccessible (msaa) functions: http://www.pinvoke.net/search.aspx?search=iaccessible&namespace=[all] here's answer along lines: msaa com-based? finally, alternative p/invoke, might able use tlbimp.exe create wrapper assembly oleacc.dll, , access msaa functions through it. i'm not sure if works msaa, it's worth try. as e...
Read more

wordpress - .htaccess: RewriteRule: bad flag delimiters -

-
pulling hair out on one. have following .htaccess file custom redirects in addition wordpress's default settings. when tested on local wamp server worked fine after moving production i'm not getting rewriterule: bad flag delimiters error in server log , after while site goes down internal server error any appreciated. in advance! <ifmodule mod_rewrite.c> rewriteengine on rewritebase / rewriterule ^rockford_weddings___welcome\.html$ /wedding/ [r=301,l] rewriterule ^blog/?$ /journal/ [r=301,l] rewriterule ^blog/(.*)$ /$1 [r=301,l] rewriterule ^portraitinvestment/?$ /portraitinvestment\.pdf [r=301,l] rewriterule ^weddinginvestment/?$ /weddinginvestment\.pdf [r=301,l] rewriterule ^holidaycards2014/?$ /holidaycards2014\.pdf [r=301,l] </ifmodule> # begin wordpress <ifmodule mod_rewrite.c> rewriteengine on rewritebase / rewriterule ^index\.php$ - [l] rewritecond %{request_filename} !-f rewritecond %{request_filename} !-d rewriterule . /index.php [l] </...
Read more