c# - How to query the average from a certain property in an Entity and return it in a List of List of objects in LINQ? -


my entities designed in entity framework this:

event

  • eventid
  • date
  • acceleration
  • intensity
  • deviceid
  • blockid
  • device
  • block

block

  • blockid
  • datestart
  • dateend
  • events

device

  • deviceid
  • alias
  • clusterid
  • cluster
  • events

cluster

  • clusterid
  • name
  • devices
  • regionid

region

  • regionid
  • name
  • clusters

an event belongs block , registered device. device belongs cluster , cluster belongs region.

what i'm trying average acceleration , average intensity of events in block, organized in objects in list, these objects must organized depending if want averages of events of block detected devices in every cluster or every region.

what kind of query in linq should use?

to make more clear, these sql string represent actions want perform

select avg(e.intensity) average blocks b, events e, devices d, clusters c, regions r b.blockid = 1 , b.blockid = e.blockid , e.uniqueid= d.uniqueid , d.clusterid  = c.clusterid group c.clusterid;  select avg(e.intensity) average blocks b, events e, devices d, clusters c, regions r b.blockid = 1 , b.blockid = e.blockid , e.uniqueid= d.uniqueid , d.clusterid  = c.clusterid , c.regionid = r.regionid group c.regionid;

maybe (linq entities)... 

from ev in db.events ev.block.blockid == 1 group ev ev.device.cluster.region.id g // group ev ev.device.cluster.clusterid g select new {     regionid = g.key, // clusterid = g.key,     averageintensity = g.average(x => x.intensity),     averageacceleration = g.average(x => x.acceleration), };

to add additional fields, e.g. name: 

group ev new { id = ev.device.cluster.clusterid, name = ev.device.cluster.name }  g

or 

group ev ev.device.cluster g   // ... clustername = g.key.name,

(sql both same)

you 'group by' many fields - since same (i.e. if id same, name same) - wouldn't change nature of grouping - additional fields attached.

normally (w/o aggregation) can add 'grouping' select group = g, , flatten , return records etc.


Comments

Post a Comment

Popular posts from this blog

Why does Ruby on Rails generate add a blank line to the end of a file? -

running rails generate controller foo home results in: class foocontroller < application controller def home end end (there's nothing on line in actual file, blank line) is there purpose blank line? it's common use newline indicate end of line, last line. many editors (like vi, use) add in newline silently. consensus text files (especially in unix world) should end in newline, , there have been problems historically if wasn't present. why should text files end newline? the tool used count lines in file "wc" counts newlines in file, without trailing newline show 3 instead of 4. it improves readability of templates used in generator. consider: https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/controller/templates/controller.rb to remove trailing newline, template have last line of: end<% end -%> instead of: end <% end -%> that seems less readable me. the discussion below refers ...
Read more

keyboard - Smiles and long press feature in Android -

i've created android keyboard. how add features inserting smilies, , using long keypresses display symbols? to create long-press behavior allows select several options pop-up menu, follow guide (specifically pop-up menu section): http://developer.android.com/guide/topics/ui/menus.html smileys (also known emoticons) combination of keys, understood programs , parsed same way. have do, when clicks smiley face on keyboard, simulate pressing of key combination matching emoticon. example, when clicks smiley, should simulate key presses ':' , ')' :). here's list of emoticons: http://en.wikipedia.org/wiki/list_of_emoticons
Read more

node.js - Bad Request - node js ajax post -

i'm using express 3.0 , node v0.11.0. have button submits form , i'm using ajax post data json object node server. client code is: $('#contact').submit(function(e) { console.log('submit called'); var formdata = json.stringify($('form').serializeobject()); console.log(formdata); $.ajax({ url: "http://localhost:3000/savedata/", type: "post", datatype: 'json', data: {objectdata: formdata}, contenttype: "application/json", complete: function() { console.log('process complete'); }, success: function(data) { console.log('process sucess'); }, error: function() { console.log('process error'); }, }); return false; }); then on server: var express = require('express'); var app = express(); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.bodyparser());...
Read more