SPARQL query restrict answers - netbeans

Question

hey im trying to get all the receipes that only contains some ingredients. For example if I have a receipe with tomato and bread and I only said that Im going to use tomate that receipe shouldnt show up. If I have any receipe with only this ingredient then it should show up. I did the following query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>`
PREFIX rec:<http://www.receta.org#>
SELECT reduced ?r
WHERE {
?x rdf:type rec:Receta .
?x rdfs:label ?r.
?x rec:Ingrediente rec:Tomato.
?x rec:Ingrediente ?i.
FILTER (?i=rec:Tomato)
}
But the problem is that it shows all the receipes that contains that ingredient and much more. How can I restrict this? Can someone help me?

Answer 1

Your first query
SELECT reduced ?r WHERE {
?x rdf:type rec:Receta .
?x rdfs:label ?r.
?x rec:Ingrediente rec:Tomato.
?x rec:Ingrediente ?i.
FILTER (?i=rec:Tomato)
}
matches any recipe that has Tomato as some ingredient. Using a filter with a constant value like that is the same as having written:
SELECT reduced ?r WHERE {
?x rdf:type rec:Receta .
?x rdfs:label ?r.
?x rec:Ingrediente rec:Tomato.
}
Instead, you want to select recipes and remove those that have ingredients other than some set. AndyS's answer mentions filter not exist, and that's a start. Specifically, if you want to ensure that all the ingredients are, e.g., Tomato, Basil, and Cheese, then you would write a query like:
SELECT reduced ?r WHERE {
?x rdf:type rec:Receta .
?x rdfs:label ?r.
filter not exists {
?x rec:Ingrediente ?i
filter( ?i not in (rec:Tomato, rec:Basil rec:Cheese) )
}
This finds all recipes, and then removes any which have an ingredient which is not one of the allowed ingredients.

Answer 2

Look at FILTER NOT EXISTS.
So something like (depends of the exact nature of your data that isn't shown):
WHERE {
?x rdf:type rec:Receta .
?x rdfs:label ?r.
FILTER NOT EXISTS {?x rec:Ingrediente rec:Tomato }
}
which is all ?x, ?r where ?x does not have property/value "rec:Ingrediente rec:Tomato".