BAP Online Manuals : Library Reference : Library by Name : database
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6.2.35. database

retrieves information from the database.

SYNOPSIS

database(Term)

SYNTAX

database(Term) (x)

ARGUMENTS

void(Term) (x) Term to be matched with database entries

DESCRIPTION

This predicate retrieves information from the database by matching its argument with any term stored in the database. Until the DATABASE keyword is implemented, you have to use this or clause to make a non-destructive database query. Database acts just like retract (), except that it does not remove the entries. You may invoke indefinite loops by using a database(X), ..., assertz(X),fail. construct.

EXAMPLE

asserta(hello),
asserta(world),
database(X),
	write(X),nl,
	fail.

ERRORS

No runtime errors.

LAYERS

prolog-process, client-server, object

RELATED PREDICATES

asserta , assertz , retract , retractall , clause , listing

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BAP Online Manuals : Library Reference : Library by Name : database
Previous: cutbacktrack
Next: dcall