It depends on what you're using it for. There's an easy solution of creating a table such as 'Spec Attributes' with just two three columns: Product Id, Spec Name, Spec Value. This would be an easy fix - but offers no support or data integrity.
A better solution would be to put some safeguards around attributes. Similar to the above, it would involve having a table which would store your 'columns' (i.e. SIM, OS Version) as rows. I would suggest having pre-defined attributes and even 'types' to confine the attributes you're using to make it easier for querying.
For Example,
DeviceTypes
DeviceTypeId | Name
01 | Camera
02 | Television
03 | Mobile Phone
Category
CategoryId | Name
01 | General
02 | Video Features
DeviceAttributeTypes
DeviceAttribTypeId| DeviceTypeId | CategoryId |AttributeName | DataType
01 | 01 | 01 | SIM | Varchar
02 | 01 | 01 | Size | NUMBER
03 | 02 | 02 | Display Size | NUMBER
04 | 02 | 01 | Model | Varchar
DeviceAttribut
DeviceId | DeviceAttirbTypeId | Value
13 | 01 | Single Sim, GSM
13 | 02 | 5
14 | 04 | 47LN5710
In this example, you would 'hard-code' the Device Types and Category tables with the attributes and types you would like. This gives you option of filtering your attributes by the Type or Category of them.
i.e. To get a list of all devices and their attributes you would could use the below query below. Then you could add in 'WHERE' on the ID's or names of categories or device types
SELECT d.DeviceName
, dat.AttributeName
, dar.Value
FROM Device d
LEFT JOIN DeviceAttribute da
ON d.DeviceId = da.DeviceId
LEFT JOIN DeviceAttributeType dat
ON da.DeviceAttribTypeId = dat.DeviceAttribtypeId
To make queries where you need to return a resultset with the attributes as columns, I always use the ;with annotation. (Example here)
