mysql中逗号分隔字段的更好替代方案

Question

In my application whenever a user upload a wallpaper,i need to crop that wallpaper into 3 different sizes and store all those paths(3 paths for cropped images and 1 for original upload wallpaper) into my database.
I also need to store the tinyurl of the original wallpaper(one which is uploaded by user).

While solving the above described problem i come up with following table structure.

CREATE TABLE `wallpapermaster` (
  `wallpaperid` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `userid` bigint(20) NOT NULL,
  `wallpaperloc` varchar(100) NOT NULL,
  `wallpapertitle` varchar(50) NOT NULL,
  `wallpaperstatus` tinyint(4) DEFAULT '0' COMMENT '0-Waiting,1-approved,2-disapproved',
  `tinyurl` varchar(40) NOT NULL
) ENGINE=MyISAM

wallpaperloc is a comma separated field consisting of original wallpaper location plus locations of all cropped instances.

I know using comma separated field considered to be a bad design in the world of relational database,So Would you like to suggest some other neat and efficient ways?

Answer 1

Use a 1:n relationship between the wallpapermaster and a location table.

Something like this:

CREATE TABLE wallpapermaster (
  wallpaperid     int unsigned NOT NULL AUTO_INCREMENT,
  userid          bigint NOT NULL,
  wallpaperloc    varchar(100) NOT NULL,
  wallpapertitle  varchar(50) NOT NULL,
  wallpaperstatus tinyint DEFAULT '0' COMMENT '0-Waiting,1-approved,2-disapproved',
  primary key (wallpaperid)
) ENGINE=InnoDB;


CREATE TABLE wallpaperlocation (
  wallpaperid  int unsigned NOT NULL,
  location     varchar(100) NOT NULL,
  tinyurl      varchar(40),
  constraint fk_loc_wp 
      foreign key (wallpaperid) 
      references wallpapermaster (wallpaperid),
   primary key (wallpaperid, location)
) ENGINE=InnoDB;

The primary key in wallpaperlocation ensures that the same location cannot be inserted twice.

Note that int(10) does not define any datatype constraints. It is merely a hint for client application to indicate how many digits the number has.

Answer 2

Usually you use a fixed location (maybe out of a config), fix extension (usually jpg ) and a special filename formats like [name]-1024x768.jpg . This way you only the the name

Answer 3

In my opinion using ; or , in siple application is quite good solution even in relational databases.

You should propably think about amout of splitted images count. If there will be less than 5 wallpapers I would not take overhead complex solutions.

• It's easy to maintain in database and application. You will use string splitting/joining methods
• No need to adding extra additional tables which you will use join to retreive values.
• Using simple varchar rather xml is better because you don't have to rely on application database access engine. When you use ORM or JDBC you have extra additional work to do to handle more complex datatypes.

In more complex systems I would make XML column.

Answer 4

While thumbnails are generated automatically from the single uploaded file, you don't need to store paths to cropped/resized files at all.

Instead you can just use normalized filenames for thumbnails and then find them in filesystem - something that KingCrunch suggested: photo1.jpg , photo1-medium.jpg etc.

Anyway, my 2cc: for avoiding traversing your image library (and created thumbnails) with some harvesters, it's good idea to encrypt name of each thumbnail even with just MD5 + some secret key programmatically, so only your program which knows the key can create proper path to the thumbnails basing on the original name/path. For other clients, naming sequence will be just random.

Answer 5

CREATE TABLE `wallpapermaster` (
  `wallpaperid` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `userid` bigint(20) NOT NULL,
  `wallpapertitle` varchar(50) NOT NULL,
  `wallpaperstatus` tinyint(4) DEFAULT '0' COMMENT '0-Waiting,1-approved,2-disapproved',
  `tinyurl` varchar(40) NOT NULL
) ENGINE=MyISAM

Create a new table which will create relationship with "wallpapermaster" table

create wallpapermaster_mapper( 
    `id` unsigned NOT NULL AUTO_INCREMENT,
    `wallpapermaster_id` int(10) //this will be foreign key with id of wallpapermaster table
    `wallpaper_path1`  varchar(100) NOT NULL,
    `wallpaper_path2`  varchar(100) NOT NULL,
    `wallpaper_path3`  varchar(100) NOT NULL,
    )