SPARQL 查询中同一列下的返回值

Question

Given three possible objects for triples, foaf:name , foaf:givenName , and foaf:familyName , where statements either have foaf:name or foaf:givenName + foaf:familyName , eg:

<uri1> <foaf:name> "Lolly Loozles" .

<uri2> <foaf:givenName> "Stotly" .
<uri2> <foaf:familyName> "Styles" .

wondering how to write a SPARQL query to return a new variable like pretty_name that is either the value of foaf:name or a concatenation of the values from foaf:givenName and foaf:familyName .

Resulting in something like:

?o     | ?pretty_name
----------------------
<uri1> | Lolly Loozles
<uri2> | Stotly Styles

This is what I have so far, but unsure how to proceed:

PREFIX : <https://example.org/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

# select two variables, not ideal...
SELECT ?foaf_fullName ?pretty_name

WHERE {    

    # Find all triples
    ?s ?p ?o .

    # Binds
    OPTIONAL { ?s foaf:name ?foaf_fullName }
    OPTIONAL { ?s foaf:givenName ?givenName }
    OPTIONAL { ?s foaf:familyName ?familyName }

    # Filter where predicate is part of list
    FILTER (?p IN (foaf:name, foaf:givenName, foaf:familyName ) )

    # Binds
    BIND( CONCAT(?givenName, ' ', ?familyName) AS ?pretty_name ) .

}

I had imagined, and tried, adding another BIND to add to ?pretty_name , but the SPARQL engine wouldn't have it:

BIND( ?foaf_fullName AS ?pretty_name ) .

I also had luck writing a CONSTRUCT statement to get the values I'm looking for, but don't have the ability to write back to this triplestore (for a number of reasons):

CONSTRUCT { 
    ?s :hasPrettyName ?foaf_fullName .
    ?s :hasPrettyName ?pretty_name .
}

I had thought that CONSTRUCT could accompany SELECT , but must have been mistaken?

Any insight or suggestions would much appreciated.

Answer 1

Using @StanislavKralin comment/suggestion to use COALESCE without IF clauses works great:

PREFIX : <https://example.org/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

# select two variables, not ideal...
SELECT ?foaf_fullName ?pretty_name

WHERE {    

    # Find all triples
    ?s ?p ?o .

    # Binds
    OPTIONAL { ?s foaf:name ?foaf_fullName }
    OPTIONAL { ?s foaf:givenName ?givenName }
    OPTIONAL { ?s foaf:familyName ?familyName }

    # Filter where predicate is part of list
    FILTER (?p IN (foaf:name, foaf:givenName, foaf:familyName ) )

    # Binds
    BIND( COALESCE(?foaf_fullName, CONCAT(?givenName, ' ', ?familyName)) AS ?pretty_name )

}