[SOLVED] Determining Day Of Week For Datetime in SPARQL

Determining Day Of Week For Datetime in SPARQL

I have a graph I am trying to filter for a report by day of week. For instance, I wish to find all the instances where they occurred on a Tuesday. Is there a way to either format the datetime field into day of week or filter by day of week directly on the datetime field?

Solution

You can also determine the day of week in standard SPARQL if you provided a bit of background knowledge. The query needs a reference date preceding your dates and the day of week at this date.

PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#>

SELECT ?date ?dayName
WHERE {
  # Sample dates
  VALUES ?date {
    "1961-08-04"^^xsd:date
    "1986-04-03"^^xsd:date
  }
  # Compute days since a reference date
  # This works in Virtuoso, which returns the difference in days.
  # For example, Fuseki returns xsd:duration instead.
  BIND (?date - "1900-01-01"^^xsd:date AS ?days)
  # Compute modulo by 7 without a modulo operator
  BIND (floor(?days - (7 * floor(?days/7))) AS ?mod)
  VALUES (?mod ?dayName) {
         (0    "Monday") # 1900-01-01 was Monday
         (6    "Tuesday")
         (5    "Wednesday")
         (4    "Thursday")
         (3    "Friday")
         (2    "Saturday")
         (1    "Sunday")
  }
}