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Newsgroups: comp.lang.ada
Subject: Re: creating database
References: <1115570998.707181.84650@o13g2000cwo.googlegroups.com>
From: Ludovic Brenta <ludovic.brenta@insalien.org>
Date: Sun, 08 May 2005 19:36:00 +0200
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Date: 2005-05-08T19:35:50+02:00
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 writes:
> hi
>
> I'm trying to create a database using ada. I'm struggling to work
> out how to implement the record type and storage. The data only has
> to be stored in main memory.
>
> I was thinking of creating the ADT as a record with various fields,
> and then an array with each element containing a record. However, I
> don't know how many records there'll be so it seems inefficient to
> declare an array of a particular size.
>
> Any advice one how to implement the database would be very much
> appreciated. As an ada novice, I'm struggling.

We do not do students' homework for them, so I'm not going to give you
"the answer" here (if you're not a student, this sentence is intended
for future readers who may be students).

Your question is not specific to Ada or any particular language.  It
is a design question.  If I understand well, you're trying to store a
variable (and unknown at compile time) number of "things" in memory.
There are many well-known data structures to choose from, or you could
roll your own.  The simplest data structure you can try is called a
"linked list".  Look it up on Google.  A linked list is simple and
efficient when adding new "things", but inefficient when searching for
one particular "thing".  Most industrial-strength database engines use
more sophisticated data structures such as B-trees (q.v., on Google).

HTH

-- 
Ludovic.