On Jun 8, 9:20 am, Michael Lang <[email protected]> wrote:
> > uninsured_codes = nil
> => nil
> > DB[:insurances].filter(:code => uninsured_codes).sql
>
> => "SELECT * FROM `insurances` WHERE (`code` IS NULL)"
>
> Good!
>
> > uninsured_codes = ['', 'NO INS', 'NO INS HS', 'HMLS-NOIN', 'NDA']
>
> => ["", "NO INS", "NO INS HS", "HMLS-NOIN", "NDA"]>
> DB[:insurances].filter(:code => uninsured_codes).sql
>
> => "SELECT * FROM `insurances` WHERE (`code` IN ('', 'NO INS', 'NO INS
> HS', 'HMLS-NOIN', 'NDA'))"
>
> Good!
>
> > uninsured_codes = [nil, '', 'NO INS', 'NO INS HS', 'HMLS-NOIN', 'NDA']
>
> => [nil, "", "NO INS", "NO INS HS", "HMLS-NOIN", "NDA"]>
> DB[:insurances].filter(:code => uninsured_codes).sql
>
> => "SELECT * FROM `insurances` WHERE (`code` IN (NULL, '', 'NO INS',
> 'NO INS HS', 'HMLS-NOIN', 'NDA'))"
>
> Above doesn't work in mysql. The record with NULL is not returned.
> Need to see:
> => "SELECT * FROM `insurances` WHERE ((`code` IN ('', 'NO INS', 'NO
> INS HS', 'HMLS-NOIN', 'NDA')) OR (`code` IS NULL))"
>
> With the above query, the NULL record is returned along with the others.
>
> Can Sequel be extended to do "OR <field> IS NULL" when an array with
> legit values as well as nil is passed?
Such a change is easy to make, but I think it is a bad idea. NULL =
NULL is not true in SQL (it is NULL). Here's a simple example:
artists = []
artists << Artist.load(:id=>1)
artists << Artist.new
artist_ids = artists.map{|a| a.id} # [1, nil]
albums_for_artists = Album.filter(:artist_id=>artist_ids).all
With your idea, albums_for_artists will be all albums for artist 1 and
all albums that don't have an artist. That's obviously not what is
desired.
Jeremy
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