dbf files and indexes

[D'Arcy J.M. Cain]

On Thu, 27 May 2010 12:45:58 -0700
Ethan Furman <ethan at stoneleaf.us> wrote:
> Let's say I have two tables:
> 
> CatLovers                DogLovers
> -------------------      -------------------
> | name      | age |      | name      | age |
> |-----------------|      |-----------------|
[...]
> 
> NumberOfPets
> ---------------------------
> | name      | cats | dogs |
> ---------------------------
[...]

First problem is learning to count.  :-)

Second (first real) problem is that you database is not normalized.  If
all of the cat lovers and dog lovers are in NumberOfPets then move the
age into that.  Probably should rename it as well.

Finally, are these SQL databases?  The best way of getting information
is with SQL.

SELECT * FROM NumberOfPets
WHERE name IN (SELECT name FROM CatLovers) OR
  name IN (SELECT name FROM DogLovers)
ORDER BY name;

> catlovers = dbf.Table('CatLovers')
> doglovers = dbf.Table('DogLovers')
> petcount  = dbf.Table('NumberOfPets')

I guess you should tell us what dbf is.  It doesn't seem to be a
standard module and it doesn't look like DB-API.  It's hard to answer
your question without knowing what these functions do.

-- 
D'Arcy J.M. Cain <darcy at druid.net>         |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
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