mysql - SQL Conditional Logic to select the 'most appropriate' record -

-

i simplified entire system shows enough particular question. i'm storing in table information 1 photo has been scaled down several times (maintain aspect ratio). i'm trying devise 1 query table can appropriate photo.

what mean appropriate is

  1. if request 705px width largest 1 returned in case 700x394

  2. if request 50px width smallest 1 returned in case 150x84

sample data photo resized dimensions

  700x394   400x200   300x169   150xx84

more information

  • the images in database proportionally resized down using reference edge.
  • the reference edge longest edge means if receive portrait photo gets resized down proportionally *x700, *x400, *x300, *x150.
  • if image landscape gets resized down same way 700x*, 400x*, 300x*, 150x*

this query partially works 0 maximum edge or lower. doesn't work if request dimension that's on maximum width.

select * images width >= 750 order width asc limit 1

i have working trick change logic based on portrait or landscape

ifnull(((width >= height , width >= $length ) or (width <= height , height >= $length )), true)

i have sql fiddle have question/problem outlined available here

any insight appreciated. understand read in data , logic in back-end language such php on high demand data pipe , want minimize overhead.

fiddle: http://sqlfiddle.com/#!9/91ca9/2

try this

select *  images order abs(width-750) asc limit 1

using absolute value of width minus requested dimension return nearest image size. i'm sure adapt need check height also


Comments

Post a Comment

Popular posts from this blog

Java 3D LWJGL collision -

-
i making 3d java game lwjgl library, , wondering how add collision detection, player not go through models. i using obj models. here objloader class, loads models: package renderengine; import java.io.bufferedreader; import java.io.file; import java.io.filenotfoundexception; import java.io.filereader; import java.util.arraylist; import java.util.list; import models.rawmodel; import org.lwjgl.util.vector.vector2f; import org.lwjgl.util.vector.vector3f; public class objloader { public static rawmodel loadobjmodel(string filename, loader loader){ filereader fr = null; try { fr = new filereader(new file("res/"+filename+".obj")); } catch (filenotfoundexception e) { system.err.println("couldn't load file!"); e.printstacktrace(); } bufferedreader reader = new bufferedreader(fr); string line; list<vector3f> vertices = new arraylist<vector3f...
Read more

spring - SubProtocolWebSocketHandler - No handlers -

-
i have ugly error during deploying spring app on jboss. 18:11:16,025 error [org.apache.catalina.core.containerbase.[jboss.web].[default-host].[/consumer]] (msc service thread 1-7) exception sending context initialized event listener instance of class org.springframework.web.context.contextloaderlistener: org.springframework.context.applicationcontextexception: failed start bean 'subprotocolwebsockethandler'; nested exception java.lang.illegalargumentexception: no handlers @ org.springframework.context.support.defaultlifecycleprocessor.dostart(defaultlifecycleprocessor.java:176) [spring-context-4.1.3.release.jar:4.1.3.release] @ org.springframework.context.support.defaultlifecycleprocessor.access$200(defaultlifecycleprocessor.java:51) [spring-context-4.1.3.release.jar:4.1.3.release] @ org.springframework.context.support.defaultlifecycleprocessor$lifecyclegroup.start(defaultlifecycleprocessor.java:346) [spring-context-4.1.3.release.jar:4.1.3.release] @ org.s...
Read more

methods - python can't use function in submodule -

-
my folder structure this: pythonstuff/ program.py modulea/ __init__.py foo.py bar.py here's code bar.py : def hello(): print("hello, world!") here's code program.py : #!/usr/bin/env python3 modulea import bar bar.hello() i run $ python3 program.py somehow error: file "program.py", line 3, in <module> bar.hello() attributeerror: 'module' object has no attribute 'hello' edit: __init__.py file empty. edit2: after trying realized had bar.py in root directory contained hello() method. bar.py in modulea/ directory empty. add it import os __all__ = [] module in os.listdir(os.path.dirname(__file__)): if module != '__init__.py' , module[-3:] == '.py': __all__.append(module[:-3]) the init .py files required make python treat directories containing packages; done prevent directories common name, such string, unintentionally hiding v...
Read more