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Finding associations

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psivyer

Programmer
Jul 7, 2005
7
GB
Hello
Newbie to Prolog - never used it yet! - however, looks interesting.

I was wondering if Prolog can be used to solve my query below. I write many many queries in sql
and it would be great if I could select a known field and something like Prolog could throw out the tables and joins referring to a given field.

For example - assume the following query ............
select
table1.name,
table4.currency
from
table1
inner join table2 on table1.id = table2.id and table1.ref = table2.ref
inner join table3 on table2.ref = table3.ref
inner join table4 on table1.id = table4.id

Is there a way in Prolog to show Ancestors and Predecessors when I ask the question something like ...
?- table4.currency
I would like to see an output something like .....

table2 on table1.id = table2.id and table1.ref = table2.ref,
table3 on table2.ref = table3.ref,
inner join table4 on table1.id = table4.id

.. as these are the tables required to get to table4.currency

equally - if I ask a different question of Prolog - eg
?- table1.name
I would still like to see all the tables and joins associated with this field - so, the output would still be the same
table2 on table1.id = table2.id and table1.ref = table2.ref,
table3 on table2.ref = table3.ref,
inner join table4 on table1.id = table4.id

Hope the above makes some sort of sense and if possible what would be the intial structure be like in order to throw
questions at it via Prolog.

Regards
Phil
 
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