This query is similar to query 3-2-implicit, but uses anonymous node notation in order to omit the ?item subject term variable. By doing so, the meaning of this query is significantly changed, as can be seen by the result set.
How to read the aggregation in this query?
- We are dealing with aggregation, because at least one aggregation function (count) appears.
- No group by clause appears, so we are dealing with implicit grouping.
- Implicit grouping means grouping around the set of variables that are visible and not argument to an aggregation function. In this case, this set of variables is ∅ (the empty set).
- Grouping based on the empty set means that all results are part one one big group. So this query counts the number of names in the entire dataset.