sql - Perform a query with aggregation and grouping by joined tables -


currently i'm facing sql challenge , wondering, if approach correct @ all. let's consider following simplified data model:

table cat: ---------- id color  table domestic_cat: ------------------- cat_id domestic_attribute  table persian_cat: ------------------ cat_id persian_attribute

and let's suppose have following data in tables:

table cat: id   color -------------- 1    'black' 2    'white' 3    'black' 4    'white' 5    'black' 6    'red' 7    'white' 8    'white' 9    'red' 10   'black'  table domestic_cat: cat_id    domestic_attribute ---------------------------- 1         'domestic1' 2         'domestic2' 3         'domestic3' 7         'domestic4' 8         'domestic5'  table persian_cat cat_id    persian_attribute --------------------------- 4         'persian1' 5         'persian2' 6         'persian3' 9         'persian4' 10        'persian5'

i perform aggregation query following result:

cat_type       cat_color   count --------------------------------- 'domestic_cat'    'black'       2 'domestic_cat'    'white'       3 'persian_cat'     'white'       1 'persian_cat'     'black'       2 'persian_cat'     'red'         2

as can see, want group 'count'-result following values: - fact, whether given cat domestic or persian - cat's color

the first 1 hard thing - don't know if it's possible @ perform "group joined table"? i'm breaking head cannot find solution :( actual rdbms used oracle 11.

you can use outer joins cat both other tables, , determine table got match, , use populate cat_type column:

select case when dc.cat_id not null 'domestic_cat'     when pc.cat_id not null 'persian_cat' end cat_type,   c.color,   count(*) "count" cat c left join domestic_cat dc on dc.cat_id = c.id left join persian_cat pc on pc.cat_id = c.id group case when dc.cat_id not null 'domestic_cat'     when pc.cat_id not null 'persian_cat' end,   c.color order 1,2;

sql fiddle.

depending on real-world problem might perform better inner join/union option, you'd need try both see better (faster, more efficient, more maintainable...).


Comments

Post a Comment

Popular posts from this blog

c# - Send Image in Json : 400 Bad request -

from android trying send image class of data, iis webservice. (c#) the problem 400 bad request . the image being encoded base64 . , placed json rest of class elements. my guess base64 not valid inside json. server not understand it. if set string "" , post accepted fine. so question is, how make base64 valid within json array? ( tried url.encode no success). or how should send image android webservice? gson gson = new gson(); string json = gson.tojson(record); // record has param { string base64photo } how big image? i'm pretty sure surpassing iis json size limit (default 4 mb). check http://geekswithblogs.net/frankw/archive/2008/08/05/how-to-configure-maxjsonlength-in-asp.net-ajax-applications.aspx or http://www.webtrenches.com/post.cfm/iis7-file-upload-size-limits good luck!
Read more

javascript - addthis share facebook and google+ url -

i attempting use addthis create simple url shares whichever current page user on when click share button. of right now, have twitter working. when user clicks, able see url populated in tweet box. when user clicks facebook or google+, url doesn't seem show in share box. <ul class="addthis_toolbox addthis_default_style "> <li><a class="addthis_button_facebook"><img src="/img/facebook-social.png" width="20" height="20" border="0" alt="share" /></a></li> <li><a class="addthis_button_twitter"><img src="/img/twitter-social.png" width="20" height="20" border="0" alt="share" /></a></li> <li><a class="addthis_button_google_plusone_share"><img src="/img/google-social.png" width="20" height="20" border="0" alt="s...
Read more

ios - Show keyboard with UITextField in the input accessory view -

i have buttona , when buttona clicked, want keyboard show uitextfield in inputaccessoryview. there way have keyboard show manually , set inputaccessoryview without having uitextfield initially? thanks. you cannot summon keyboard without object can become first responder. there 2 ways work around: subclass uiview , implement uikeyinput protocol in it. example: in .h file: @interface inputobject : uiview<uikeyinput> @property (nonatomic, copy) nsstring *text; @property (nonatomic, strong) uiview *inputaccessoryview; // must override inputaccessoryview , since it's readonly default @end in .m file, implement protocol: - (bool)canbecomefirstresponder { return yes; } - (bool)hastext { return [self.text length]; } - (void)inserttext:(nsstring *)text { nsstring *selftext = self.text ? self.text : @""; self.text = [selftext stringbyappendingstring:text]; [[nsnotificationcenter defaultcenter] postnotificationname:kinputobjec...
Read more