mysql - Many JOINs in a long SQL call -


there 4 tables, each tuple id(int),name(varchar) (the id autoincrementing). there table meal (cheeseburger, hamburger, meat feast, blt, tomato soup), class (burger, pizza, sandwich, soup), characteristics (spicy, vegtarian, gluten free), , sides(salad, fries, bread).

three more tables exist make tuples meal.id,class.id, meal.id,characteristics.id, meal.id,sides.id meal can in more 1 class, have more 1 characteristic, , come more 1 side, , vice versa.

i had following lazy loading fine, know that's not good. want name of meal, it's characteristics, sides , alternative meals same class.

this call worked fine:

select group_concat(distinct m2.meal_name separator ',')          alternates,        group_concat(distinct c.characteristic_desc separator ',')        characteristics   meal m        inner join mealclass mc                on m.meal_id = mc.meal_id        left join (select meal_id,                          class_id                     drugingredient) mc2               on mc2.class_id = mc.class_id        left join meals m2               on mc2.meal_id = m2.meal_id        left join mealchar mch               on mch.meal_id = m.meal_id        inner join characterisics c                on c.characteristic_id = mch.characteristic_id  m.meal_id = :meal_id        , m.meal_id <> m2.meal_id

but when extended out this, got nothing back:

select group_concat(distinct m2.meal_name separator ',')          alternates,        group_concat(distinct c.characteristic_desc separator ',')        characteristics,        group_concat(distinct s.sides_desc separator ',')          side_orders   meal m        inner join mealclass mc                on m.meal_id = mc.meal_id        left join (select meal_id,                          class_id                     drugingredient) mc2               on mc2.class_id = mc.class_id        left join meals m2               on mc2.meal_id = m2.meal_id        left join mealchar mch               on mch.meal_id = m.meal_id        inner join characterisics c                on c.characteristic_id = mch.characteristic_id        inner join mealsides ms                on m.meal_id = ms.meal_id        inner join sides s                on s.sides_id = ms.sides_id  m.meal_id = :meal_id        , m.meal_id <> m2.meal_id

any ideas how fix call, or how have better structured schema? or degree of lazy loading best way go here (:p)?!

there 3 possible things here. i've written them out demonstration.

create table (x integer, y integer); create table b (v integer, w integer); create table c (t integer, u integer); insert values (1,2); insert values (3,4); insert values (5,6); insert b values (1,2); insert b values (5,6); insert c values (1,2); insert c values (3,4);

this same used:
(a left join b) join c 

select * left join b on a.x = b.v join c on b.v = c.t;  x | y | v | w | t | u ---+---+---+---+---+---  1 | 2 | 1 | 2 | 1 | 2

this using left joins:
(a left join b) left join c 

select * left join b on a.x = b.v left join c on b.v = c.t;  x | y | v | w | t | u ---+---+---+---+---+---  1 | 2 | 1 | 2 | 1 | 2  3 | 4 |   |   |   |  5 | 6 | 5 | 6 |   |

i think aiming for: left join (b join c)

select * left join (b join c on b.v = c.t) on a.x = b.v;  x | y | v | w | t | u ---+---+---+---+---+---  1 | 2 | 1 | 2 | 1 | 2  3 | 4 |   |   |   |  5 | 6 |   |   |   |

hope helps


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