SPARQL ASK查询中的多个条件

Question

I need to include few conditions in SPARQL ASK query.

I tried --

• nesting a few ASK queries
• nesting SELECT statement inside ASK query
• just putting all the conditions in ASK query

-- but the answer is always wrong.

I've checked all the conditions one by one and it's working, so the problem is just in query construction.

Approximately this is what I want:

PREFIX m: <http://data.linkedmdb.org/resource/movie/>
ASK
  {
    ?kraj  m:country        "United Kingdom".
    ?rez   m:director_name  ?rezyser .
    FILTER regex(?rezyser, "James", "i")
  }

How can I make it work?

Answer 1

If you simply put multiple clauses in the WHERE clause of any SPARQL query then you are asking that ALL those clauses must be satisfied in order for an answer to be returned.

It sounds like what you actually want to know is if ANY of those clauses are satisfied in which case you need to use the UNION operator eg

PREFIX m: <http://data.linkedmdb.org/resource/movie/>
ASK
{
  {
    ?kraj m:country "United Kingdom".
  }
  UNION
  {
    ?rez m:director_name ?rezyser.
    FILTER regex(?rezyser, "James", "i")
  }
}

You can have as many branches in your UNION as you need, for example if you wanted to check if any of 4 clauses were satisfied:

ASK
{
  {
    # Clause 1
  }
  UNION
  {
    # Clause 2
  }
  UNION
  {
    # Clause 3
  }
  UNION
  {
    # Clause 4
  }
}