Re^2: Query database in Prolog

What I was imagining was using Prolog in place of RDBMS. That is a prolog engine to which you could connect using an analogue to ODBC, store facts there and query them. But this means you need a way to delete the facts as well - I don't know how this can be added to the Prolog computational model. I just started with Prolog and I don't really understand your sentence about backtracking over query results - but I think that backtracking in this environment would have to be limited by a transaction boundary.

Comment on Re^2: Query database in Prolog

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Re^3: Query database in Prolog by Ovid (Cardinal) on Dec 29, 2005 at 21:43 UTC
In reality, deleting facts is generally not something one wants to do as it's considered a "non-logical" operation. However, you can use `retract/1` if you really need to: `AI-NeuralNet-Simple-0.03 $ aiprolog Welcome to AI::Prolog v 0.732 Copyright (c) 2005, Curtis "Ovid" Poe. AI::Prolog comes with ABSOLUTELY NO WARRANTY. This library is free so +ftware; you can redistribute it and/or modify it under the same terms as Perl +itself. Type '?' for help. ?- help('retract/1') retract/1 Remove facts from the database. You cannot remove rules. This may change in the future. See assert(X). retract(loves(ovid,java)). help(retract/1) Yes ?-` [download] You can also just type "help" at the `aiprolog` prompt to see a list of all built-in predicates you can get help for: `?- help. Help is available for the following builtins: !/0 assert/1 call/1 consult/1 div/2 eq/2 fail/0 ge/2 gt/2 halt/1 if/3 is/2 le/2 listing/0 listing/1 lt/2 minus/2 mod/2 mult/2 ne/2 nl/0 not/1 notrace/0 once/1 or/2 plus/2 pow/2 print/1 println/1 retract/1 trace/0 true/0 var/1 write/1 writeln/1 help Yes ?-` [download] If you really want to get a decent grounding in Prolog, see Amzi's "Adventure in Prolog". It's a free online book which lets guides through building four different Prolog applications. It's quite cool. Most of the basics work in AI::Prolog, but it could still use a lot of work/patches. Cheers, Ovid New address of my CGI Course.	[reply] [d/l] [select]

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Re^3: Query database in Prolog
by Ovid (Cardinal) on Dec 29, 2005 at 21:43 UTC

In reality, deleting facts is generally not something one wants to do as it's considered a "non-logical" operation. However, you can use retract/1 if you really need to:

AI-NeuralNet-Simple-0.03 $ aiprolog 


Welcome to AI::Prolog v 0.732
Copyright (c) 2005, Curtis "Ovid" Poe.
AI::Prolog comes with ABSOLUTELY NO WARRANTY.  This library is free so
+ftware;
you can redistribute it and/or modify it under the same terms as Perl 
+itself.

Type '?' for help.

?- help('retract/1') 

retract/1

    Remove facts from the database. You cannot remove rules. This may
    change in the future. See assert(X).

     retract(loves(ovid,java)).

help(retract/1) 

Yes
?-
[download]

You can also just type "help" at the aiprolog prompt to see a list of all built-in predicates you can get help for:

?- help.

Help is available for the following builtins:

!/0          assert/1     call/1       consult/1    div/2    
eq/2         fail/0       ge/2         gt/2         halt/1   
if/3         is/2         le/2         listing/0    listing/1
lt/2         minus/2      mod/2        mult/2       ne/2     
nl/0         not/1        notrace/0    once/1       or/2     
plus/2       pow/2        print/1      println/1    retract/1
trace/0      true/0       var/1        write/1      writeln/1

help 

Yes
?-
[download]

If you really want to get a decent grounding in Prolog, see Amzi's "Adventure in Prolog". It's a free online book which lets guides through building four different Prolog applications. It's quite cool. Most of the basics work in AI::Prolog, but it could still use a lot of work/patches.

Cheers,
Ovid

New address of my CGI Course.

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