Re: Sorting by an arbitrary criterion

2009/7/9 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> =?UTF-8?Q?Grzegorz_Ja=C5=9Bkiewicz?= <gryzman(at)gmail(dot)com> writes:
>> On Thu, Jul 9, 2009 at 5:26 PM, Craig James<craig_james(at)emolecules(dot)com> wrote:
>>> Suppose I have a large table with a small-cardinality CATEGORY column (say,
>>> categories 1..5).  I need to sort by an arbitrary (i.e. user-specified)
>>> mapping of CATEGORY, something like this:
>
>> you can create translation table, join it, and sort by its key.
>
> Much easier to
>        ORDER BY CASE category WHEN 'z' THEN 1 WHEN 'a' THEN 2 ... END
>
> Actually, consider putting the CASE into a function and doing
>        ORDER BY sort_order(category)

I suppose table is handy, when you have a lot of items as keys...

--
GJ