mysql - Sorting result with absolute placement -


http://sqlfiddle.com/#!2/1840d/1

i have table of ids , places, possible rows set @ specified places?

to get

id  place 5   (null) 3   2 4   (null) 6   4 2   (null) 1   (null)

instead of

id  place 6   4 5   (null) 4   (null) 3   2 2   (null) 1   (null)

for data means have row place = 2 second row in result , row place = 4 fourth in result, while other rows cover them in original order.

answer 

select * records  order field(id, 5,3,4,6,2,1)

is nice , funny, wrong.

select case when nullid null         id        else nullid        end id,         tofilltable.place  (     select case when id null             @placeholder := @placeholder + 1             else null             end placeholder          , r.*         (         select @row := @row + 1 row         records t1, (select @row := 0) t2     ) s         inner join (select @placeholder := 0) t12         left outer join records r             on s.row = r.place     order row ) tofilltable     left outer join     (           select @row1 := @row1 + 1 nullrowplace, t1.id nullid           records t1, (select @row1 := 0) t2           place null           order t1.id desc     ) nullplacetable on tofilltable.placeholder = nullplacetable.nullrowplace

the first query output result :

tofilltable  placeholder    id    place     1        (null)  (null)   (null)       3       2     2        (null)  (null)   (null)       6       4     3        (null)  (null)     4        (null)  (null)

it gives id when place given on right row, , give counter named placeholder on row place null.

the second query:

nullplacetable   nullplaceholder    idnull      1                5      2                4      3                2      4                1

it gives rank of row when place null.

the join of 2 gives expected!

fiddle.

reference:


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