Question

Using the table code below I was asked to draw out a list sorted by the rankings of each item. Each column rank# is how each user would rank that item. So for an item A if it was ranked 1 by one user and 16 by another its overall ranking should be 8. Is there a possible SQL query for this or process it in PHP?

CREATE TABLE `rankings` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `userId` int(11) NOT NULL,
  `rank1` int(11) NOT NULL,
  `rank2` int(11) NOT NULL,
  `rank3` int(11) NOT NULL,
  `rank4` int(11) NOT NULL,
  `rank5` int(11) NOT NULL,
  `rank6` int(11) NOT NULL,
  `rank7` int(11) NOT NULL,
  `rank8` int(11) NOT NULL,
  `rank9` int(11) NOT NULL,
  `rank10` int(11) NOT NULL,
  `rank11` int(11) NOT NULL,
  `rank12` int(11) NOT NULL,
  `rank13` int(11) NOT NULL,
  `rank14` int(11) NOT NULL,
  `rank15` int(11) NOT NULL,
   `rank16` int(11) NOT NULL,
  `submissionTimestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=latin1;

Here is the table that each rank# column is referenced to:

CREATE TABLE `rankableItems` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`itemName` varchar(30) NOT NULL DEFAULT '',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=latin1;

Answer 1

I think you take it the wrong way. Here what you could do that will be much more simple to work with and to understand :

create table `ranking` (
    `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
    `user_id` int(11) unsigned NOT NULL,
    `item_id` int(11) unsigned NOT NULL,
    `item_rank` int(11) unsigned NOT NULL
)

And the associated query to get the average ranking :

SELECT AVG(item_rank) AS AVG_RANK 
FROM ranking 
WHERE item_id = 'xxx'