bind-calculation in the projection
Renaming variable projection
The unbound variable projection
Quad triple pattern retrieval abbreviated
Quad triple pattern retrieval
Two triple pattern retrieval
The generic projection
The generic projection (
select *) is used to include one column for every visible variable in the pattern component.
The order in which the columns are returned is not specified in the SPARQL standard and is implementation-specific. Often, columns are returned in the order in which the corresponding variables appear for the first time inside the pattern component, but this is not guaranteed. If the order of the columns is important, it is more robust to specify the variables explicitly.
Projection: add/remove columns
This query only returns one column. This one column contains the colors of Pokémon (bindings for variable
?pokemon variable is used in the graph pattern, but its bindings are not returned in the projection. Variables like
?pokemon that are internal to the pattern component and are not exposed in the projection are called hidden variables.
Result sets must contain of at least one column. The same column may be included more than once.
Projection: column order
Like this query, but with the order of the columns inverted: the projection specifies which columns are included in the result set, and also specifies the order in which they appear.
Abbreviation: IRI prefix notation
Identical to this query, but the lengthy predicate term that was used there is now abbreviated using alias (
measure). This requires that the alias and IRI prefix are declared at the top of the query (keyword
The part of the query that appears before the projection, and that contains prefix declarations, is called the Prologue.
Notice that another IRI prefix
observation is also declared. This prefix is not used in the query itself, but is used to abbreviate the values that appear the first column of the result set table. (This is a Triply-specific feature.)
Binding a variable
bind keyword allows variables to be introduced that do not appear in a graph pattern.
Observations with a specific petal length
A table of observations and their petal length
select query that returns observations (bindings for the variable
?observation) and their colors (bindings for the variable
?petalLength), in that order.
Notice how the predicate term (i.e., the middle term) is bound to a specific IRI (
<https://triplydb.com/triply/iris/def/measure/petalLength>) that denotes the relationship between things and their depiction.
The first SPARQL select query
This is a very simple
select query. But it already contains all three main
select query components:
- The columns that are returned (
select ?s ?p ?o)
- Triple Pattern
- How the cells will be filled based on graph matching (
?s ?p ?o.)
- Result set modifiers
- Adaptations to the result table (