Question

I want to structure a table to mimic column level filters as row level filter just to avoid adding new columns.

Let’s say i have following table to store cars’ details

-------------------------------------
Type        Color       Year
-------------------------------------
Mini        Silver      2010
Standard    Silver      2011
Fullsize    White       2011
Luxury      Black       2010
Sports      Red     2011
Convertible Red     2009

If i want to store Make of these cars as well and for this i have to add an additional column and another column if i have automobiles other than cars.

So the question is how can i structure this table to avoid adding new columns? The structure should require only to add rows to define properties of my records.

[Hint] The structure may have multiple tables, one to store rows/records and other to store columns/properties and then some kind of mapping between them OR entirely new structure.

EDIT

Some of the properties of my data are fixed and some are dynamic. Fixed properties can be mapped to the given sample Car model as Availability, Condition and the dynamic could be anything which a person may ask about an automobile. Now i don’t need all columns to be mapped as rows but few and these are dynamic and i don’t even know all of them. My apologies that i didn’t mention this earlier.

Answer 1

You could use the entity-attribute-value design (EAV).

entity  attribute   value
1       Type        Mini
1       Color       Silver
1       Year        2010
1       Make        Foobar
2       Type        Standard
2       Color       Silver    
etc...

You may also wish to store the attribute names in a separate table.

However you should consider carefully if you really need this, as there are a few disadvantages. The value column must have a type that can store all the different types of values (e.g. string). It is much more cumbersome to write queries as you will need many joins, and these queries will run more slowly as compared to a traditional database design.