Vertex and Edge Labels with PGQL

Labels are a way of attaching type information to edges and nodes in a graph, and can be used in constraints in graphs where not all nodes represent the same thing. For example:

SELECT p.name
FROM MATCH (p:person) -[e1:likes]-> (m1:movie),
     MATCH (p) -[e2:likes]-> (m2:movie)
WHERE m1.title = 'Star Wars'
  AND m2.title = 'Avatar'

The example queries a graph which contains a set of vertices with the label person, a set of vertices with the label movie, and a set of edges with the label likes. A label expression can start with either a colon (:) or the keyword IS followed by one or more labels. If more than one label is used, then the labels are separated by a vertical bar (|).

The following query shows the preceding example query with the keyword IS for the label expression:

SELECT p.name
FROM MATCH (p IS person) -[e1 IS likes]-> (m1 IS movie),
     MATCH (p IS person) -[e2 IS likes]-> (m2 IS movie)
WHERE m1.title = 'Star Wars'
  AND m2.title = 'Avatar'

See Also: Label Expression section in the PGQL specification