What is the blank nodes utility in SPARQL queries?
[] is syntax for "new blank node" each time it is used.
In that example, each [] is a different blank node. The query is much the same as two different variables.
SELECT ?first ?last ?workTel
WHERE {
?VAR_1 ab:firstName ?first ;
ab:lastName ?last .
OPTIONAL
{?VAR_2 ab:workTel ?workTel . }
}
No connection is formed between the two parts of the query.