arangodb的graph之一

A Graph consists of vertices and edges.
graph分爲named graphs，anonymous graphs
AQL Graph Operations 包含兩種：
AQL Traversals 遍歷
AQL Shortest Path 最短路徑
vertex，vertice，document是近義詞
edge，relation是近義詞
aql Traversals 語法：
[WITH vertexCollection1[, vertexCollection2[, …vertexCollectionN]]]
FOR vertex[, edge[, path]]
IN [min[…max]]
OUTBOUND|INBOUND|ANY startVertex
GRAPH graphName
[OPTIONS options]
或者：
[WITH vertexCollection1[, vertexCollection2[, …vertexCollectionN]]]
FOR vertex[, edge[, path]]
IN [min[…max]]
OUTBOUND|INBOUND|ANY startVertex
edgeCollection1, …, edgeCollectionN
[OPTIONS options]