On 2-Sep-10, at 3:54 PM, Tom Murphy wrote:

Hi Everyone,

   Is there a "From SQL"-type function that "restores" a range or list comprehension?

Example:
Let's say I want to keep track of which episodes of a TV show I've seen. I have an SQL table, in which is a record:

   id (INTEGER): 30
   title (VARCHAR): "The Simpsons"
   episodes_watched (Some data format): [1..4], [14], [18..21], [23..25]

To model this relationally, episodes_watched cannot be some kind of composite value. You need two relations, for example:

CREATE TABLE tv_show (

id INTEGER NOT NULL, -- etc

title VARCHAR(80),

PRIMARY KEY (id)

);

CREATE TABLE episodes_watched (

tv_show_id INTEGER NOT NULL,

episode_number INTEGER,

PRIMARY KEY (tv_show_id, episode_number)

-- and ideally a foreign key constraint

);

Data:

tv_show (30, "The Simpsons")

episodes_watched (30,1), (30,2), (30,3), (30,4), (30,14), (30,18), (30,19), (30,20), (30,21), (30,23), (30,24), (30,25)

--Toby

Then, when I pull the record, in Haskell, the "Episodes Watched" is already one list:

[1,2,3,4,14,18,19,21,23,24,25]

, or a series of lists that I can append together:
[1,2,3,4], [14], [18,19,20,21], [23,24,25]

Note in the example that I would like to be able to store multiple ranges within a single record.

Thanks so much for any help!
Tom
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