Question

I have two tables that looks like this:

Table: items

id | itemId
---|------
0  | 1
1  | 2
2  | 3

Table: item_specs

id | itemId | key          | values
---|--------|---------------
0  | 1      | itemreceived | 2012-06-01
1  | 1      | modelyear    | 1992
2  | 1      | model        | 2
3  | 2      | itemreceived | 2012-06-05
4  | 2      | modelyear    | 2003
5  | 2      | model        | 1
6  | 3      | itemreceived | 2012-07-05
7  | 3      | modelyear    | 2000
8  | 3      | model        | 3

My current query looks like this:

SELECT items.*, item_specs.* FROM item_specs
INNER JOIN item_specs ON items.itemId = item_specs.itemId
WHERE itemId IN(1,2,3)

How can I order the result by a key value, for example: model?

The result I’m looking for is something like this: (if I order by model)

id | itemId | key          | values
---|--------|---------------
3  | 2      | itemreceived | 2012-06-05
4  | 2      | modelyear    | 2003
5  | 2      | model        | 1
0  | 1      | itemreceived | 2012-06-01
1  | 1      | modelyear    | 1992
2  | 1      | model        | 2
6  | 3      | itemreceived | 2012-07-05
7  | 3      | modelyear    | 2000
8  | 3      | model        | 3

The content that is returned is ordered by the value that is that has the key model

Answer 1

You need the model number for every row. You can do that with a join:

SELECT items.*, item_specs.* 
FROM item_specs
INNER JOIN item_specs ON items.itemId = item_specs.itemId
INNER JOIN item_specs aux ON (aux.key = 'model' and aux.itemID = item_specs.itemId)
WHERE item_specs.itemId IN(1,2,3)
ORDER BY aux.values/*this is the model*/, item_specs.id;

or with a subselect:

SELECT items.*, 
       item_specs.*, 
       (select aux.values 
        from item_specs aux 
        where aux.key = 'model' and aux.itemID = item_specs.itemId
        ) as model
FROM item_specs
INNER JOIN item_specs ON items.itemId = item_specs.itemId
WHERE item_specs.itemId IN(1,2,3)
ORDER BY model, item_specs.id;