SPARQL string search

Question

hi all, I have a disease class and a datatype property "complication" //range is string Can anyone please help me by providing me the SPARQL query to find all complications that contains some specified string like "abc". same as "like operator in sql"

Accepted Answer

9

You should use REGEX() in a FILTER but you may need to use the STR function to force the variable to be a string or REGEX() will not match non-literal values:

SELECT ?disease
WHERE {
   ?disease namespace:complication ?value.
   FILTER (REGEX(STR(?value), "abc", "i"))
}

See the specification for REGEX() which states it operates over simple literals, if the value bound to ?value is a URI then the REGEX() will not match on it unless you use STR(?value) to force ?value to a String

link

answered 19 Feb '11, 14:36

Rob Vesse ♦
11.8k●6●15
accept rate: 28%

It works... thanks Rob Vesse♦ for the sample code and explanation.

(19 Feb '11, 15:18) ahmedsaud

Actually, you might not need the STR clause for a couple of reasons, 1 that the property in question is a datatype property and 2 the range of that property is a string, so if the data is being reasoned over at query time or creation time, then the reasoner will infer that the value is of type string (or it might blow up if its not). Its probably good practice to keep it in, but there might be an overhead in performance.

(19 Feb '11, 19:02) William Greenly

Additionally, if the value is a URI and we know that property is a datatype property, then chances are the assertion is a mistake and logically you would want it ignored by the filter, not explicitly casted to a string, matched and included in a result.

(19 Feb '11, 19:08) William Greenly

It depends whether you want to regex within a URI or not. Even if something is inferred to be a string i.e. "literal"^^xsd:string it still needs casting with STR() as REGEX operates on simple literals i.e. "literal" so we still need STR() to strip off the datatype

(20 Feb '11, 10:50) Rob Vesse ♦

According to the spec, it should operate the same as a fn:matches which in turn operates as follows:

$input as xs:string?, $pattern as xs:string

Think it might be casting anyway??? So it will probably end up being implementation specific???

(20 Feb '11, 11:35) William Greenly

Thanks Rob!

(16 Feb, 02:09) altruist

There is no automatic casting from IRIs to strings.

(17 Feb, 09:07) AndyS ♦

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Answer 2

3	`SELECT ?disease WHERE { ?disease namespace:complication ?value. FILTER regex(?value, "abc", "i") }` You can play around with the regex as much as you want. link answered 19 Feb '11, 13:23 William Greenly 4.9k●3●12 accept rate: 13%

Answer 3

1	regex is your friend… link answered 19 Feb '11, 12:52 AB 1.6k●2●10 accept rate: 35% It doesn't provide me the results (19 Feb '11, 12:58) ahmedsaud

SPARQL string search

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