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Syntax for nested IF statements in SPARQL

I am trying to run the following SPARQL query, but it keeps returning SR171: Transaction timed out.

SELECT ?isBusAvailable WHERE {
  SELECT DISTINCT IF (
  (
  SELECT ?value2 WHERE {
      GRAPH data: { ?obsValueID2 ontology:value ?value2 }
      GRAPH data: { ?obsValueID2 rdf:label "Availability" }
      GRAPH data: { ?obsValueID2 ontology:isObservedValueOf ?obsID2}
      GRAPH data: { ?obsID2 ssn:observationResultTime ?time2 }
      GRAPH data: { ?obsID2 ssn:observedBy ?id2 }
      GRAPH meta: { ?id2 rdf:label "MyBusService" } 
  } ORDER BY DESC (?time2) LIMIT 1) > 1, "Take Bus", (
                       SELECT ?isBikeAvailable WHERE {
                       SELECT DISTINCT IF (
                       (
                       SELECT ?value3 WHERE {
                            GRAPH data: { ?obsValueID3 ontology:value ?value3 }
                            GRAPH data: { ?obsValueID3 rdf:label "Availability" }
                            GRAPH data: { ?obsValueID3 ontology:isObservedValueOf ?obsID3}
                            GRAPH data: { ?obsID3 ssn:observationResultTime ?time3 }
                            GRAPH data: { ?obsID3 ssn:observedBy ?id3 }
                            GRAPH meta: { ?id3 rdf:label "MyBikeService" } 
                       } ORDER BY DESC (?time3) LIMIT 1
                       ) > 0, "Take Bike", "Take Taxi") as ?isBikeAvailable WHERE { ?1 ?2 ?3}})) as ?isBusAvailable WHERE { ?4 ?5 ?6}}

If I run them separately, it starts in less than 1 second. The following example works.

SELECT ?isBusAvailable WHERE {
  SELECT DISTINCT IF (
  (
  SELECT ?value2 WHERE {
      GRAPH data: { ?obsValueID2 ontology:value ?value2 }
      GRAPH data: { ?obsValueID2 rdf:label "Availability" }
      GRAPH data: { ?obsValueID2 ontology:isObservedValueOf ?obsID2}
      GRAPH data: { ?obsID2 ssn:observationResultTime ?time2 }
      GRAPH data: { ?obsID2 ssn:observedBy ?id2 }
      GRAPH meta: { ?id2 rdf:label "MyBusService" } 
  } ORDER BY DESC (?time2) LIMIT 1) > 1, "Take Bus", 'Take Bike') as ?isBusAvailable WHERE { ?4 ?5 ?6}}

If the result of the first query is correct, return "Take Bus"; else, run the second request and return "Take Bike" or "Take Taxi".

Obviously, the problem is related to the second request (from the false condition of the first request). After Take Bus, if I changed the second request to Take Bike, it works.

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2 answers

@andrei - , ?isBusAvailable - , , ?travelMethod.

, , IFs - , , " IF- SPARQL?"

, "Take bus", ; , " ", ; , " ". psuedo-, IF AVAIL bus, THEN take bus, ELSE ( IF AVAIL bike, THEN take bike, ELSE take taxi ).

@joshua-taylor - SELECT DISTINCT IF (…) , - , , ( ) -

SELECT DISTINCT ( IF ( ( 1 = 1 ) 
                     , "true" 
                     , "false" 
                     )           AS ?test ) 
WHERE { ?x ?y ?z } 
LIMIT 1

. , (SELECT ?value … LIMIT 1) 1 -

SELECT ?travelMethod 
   WHERE 
     { 
        SELECT DISTINCT 
                         ( IF 
                               (
                                  (
                                     1  > 0
                                  )
                               ,  "Take Bus"
                               ,  (
                                        IF (
                                              (
                                                 1  > 0
                                              )
                                           ,  "Take Bike"
                                           ,  "Take Taxi"
                                           )
                                  )
                               )  AS  ?travelMethod
                         ) 
        FROM         data: 
        WHERE        { ?1  ?2  ?3 }
     }

- (SELECT ?value … LIMIT 1) -

SELECT    ?value 
WHERE     
          {
             GRAPH data: { ?obsValueID  ontology:value              ?value          }
             GRAPH data: { ?obsValueID  rdf:label                   "Availability"  }
             GRAPH data: { ?obsValueID  ontology:isObservedValueOf  ?obsID          }
             GRAPH data: { ?obsID       ssn:observationResultTime   ?time           }
             GRAPH data: { ?obsID       ssn:observedBy              ?id             }
             GRAPH meta: { ?id          rdf:label                   "MyBusService"  } 
          }  
ORDER BY  DESC (?time) 
LIMIT     1

, - , sparql.org , , , , . , , DBpedia, !

SELECT ?travelMethod 
   WHERE 
     { 
        SELECT DISTINCT 
                         ( IF 
                               (
                                  (
                                     (  SELECT    ?value 
                                        WHERE     
                                                  {
                                                     GRAPH data: { ?obsValueID  ontology:value              ?value          }
                                                     GRAPH data: { ?obsValueID  rdf:label                   "Availability"  }
                                                     GRAPH data: { ?obsValueID  ontology:isObservedValueOf  ?obsID          }
                                                     GRAPH data: { ?obsID       ssn:observationResultTime   ?time           }
                                                     GRAPH data: { ?obsID       ssn:observedBy              ?id             }
                                                     GRAPH meta: { ?id          rdf:label                   "MyBusService"  } 
                                                  }  
                                        ORDER BY  DESC (?time) 
                                        LIMIT     1
                                     )  > 0
                                  )
                               ,  "Take Bus"
                               ,  (
                                        IF (
                                              (
                                                 (  SELECT    ?value 
                                                    WHERE
                                                              {
                                                                 GRAPH data: { ?obsValueID  ontology:value              ?value           }
                                                                 GRAPH data: { ?obsValueID  rdf:label                   "Availability"   }
                                                                 GRAPH data: { ?obsValueID  ontology:isObservedValueOf  ?obsID           }
                                                                 GRAPH data: { ?obsID       ssn:observationResultTime   ?time            }
                                                                 GRAPH data: { ?obsID       ssn:observedBy              ?id              }
                                                                 GRAPH meta: { ?id          rdf:label                   "MyBikeService"  } 
                                                              } 
                                                    ORDER BY  DESC (?time) 
                                                    LIMIT     1
                                                 )  > 0
                                              )
                                           ,  "Take Bike"
                                           ,  "Take Taxi"
                                           )
                                  )
                               )  AS  ?travelMethod
                         ) 
        FROM         data: 
        WHERE        { ?1  ?2  ?3 }
     }

, , , -

SELECT ?travelMethod 
   WHERE 
     { 
        SELECT DISTINCT 
                         ( IF 
                               (
                                  (
                                     (  SELECT    ?value 
                                        WHERE     
                                                  {
                                                     GRAPH data: { ?obsValueID  ontology:value              ?value
                                                                             ;  rdf:label                   "Availability"
                                                                             ;  ontology:isObservedValueOf  ?obsID
                                                                 . ?obsID       ssn:observationResultTime   ?time
                                                                             ;  ssn:observedBy              ?id
                                                                 }
                                                     GRAPH meta: { ?id          rdf:label                   "MyBusService"  } 
                                                  }  
                                        ORDER BY  DESC (?time) 
                                        LIMIT     1
                                     )  > 0
                                  )
                               ,  "Take Bus"
                               ,  (
                                        IF (
                                              (
                                                 (  SELECT    ?value 
                                                    WHERE
                                                              {
                                                                 GRAPH data: { ?obsValueID  ontology:value              ?value
                                                                                         ;  rdf:label                   "Availability"
                                                                                         ;  ontology:isObservedValueOf  ?obsID
                                                                             . ?obsID       ssn:observationResultTime   ?time
                                                                                         ;  ssn:observedBy              ?id
                                                                             }
                                                                 GRAPH meta: { ?id          rdf:label                   "MyBikeService"  } 
                                                              } 
                                                    ORDER BY  DESC (?time) 
                                                    LIMIT     1
                                                 )  > 0
                                              )
                                           ,  "Take Bike"
                                           ,  "Take Taxi"
                                           )
                                  )
                               )  AS  ?travelMethod
                         ) 
        FROM         data: 
        WHERE        { ?1  ?2  ?3 }
     }
+5

IF SPARQL, . "SELECT DISTINCT"

SELECT ?isBusAvailable WHERE { 
  SELECT DISTINCT (IF(
        (
         SELECT ?value WHERE {
                GRAPH data: { ?obsValueID ontology:value ?value }
                GRAPH data: { ?obsValueID rdf:label "Availability" }
                GRAPH data: { ?obsValueID ontology:isObservedValueOf ?obsID}
                GRAPH data: { ?obsID ssn:observationResultTime ?time }
                GRAPH data: { ?obsID ssn:observedBy ?id }
                GRAPH meta: { ?id rdf:label "MyBusService" } 
        } ORDER BY DESC (?time) LIMIT 1) > 0,'Take Bus', (

                       IF (
                       (
                       SELECT ?value WHERE {
                            GRAPH data: { ?obsValueID ontology:value ?value }
                            GRAPH data: { ?obsValueID rdf:label "Availability" }
                            GRAPH data: { ?obsValueID ontology:isObservedValueOf ?obsID}
                            GRAPH data: { ?obsID ssn:observationResultTime ?time }
                            GRAPH data: { ?obsID ssn:observedBy ?id }
                            GRAPH meta: { ?id rdf:label "MyBikeService" } 
                       } ORDER BY DESC (?time) LIMIT 1
                       ) > 0, "Take Bike", "Take Taxi")
                       )) AS ?isBusAvailable) FROM data: WHERE { ?1 ?2 ?3 }}

EDIT: select distinct if( ... ) SPARQL, if . : select distinct (if( ... ))

0

Source: https://habr.com/ru/post/1607808/

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