什么是Cypher？

• 官方定义：_Cypher _is a declarative graph query language that allows for expressive and efficient querying and updating of the graph store. Cypher is a relatively simple but still very powerful language. Very complicated database queries can easily be expressed through Cypher.
• 类似sql，neo4j自带查询脚本，功能强大，语法简单；

Cypher提供的能力：

• Cypher matches patterns of nodes and relationship in the graph, to extract information or modify the data.

• Cypher has the concept of identifiers which denote named, bound elements and parameters.

• Cypher can create, update, and remove nodes, relationships, labels, and properties.

• Cypher manages indexes and constraints.

基本语法

Cypher官方语法：https://neo4j.com/docs/cypher-refcard/current/

Cypher中文文档：http://neo4j.com.cn/public/cypher/neo4j_cql_create_node.html

demo

create (gao:Person{name:"gao.xx"})-[:MENTOR{since:"2014"}]->(sh:Person{name:"shuang.xx"})
create (gao)-[:MENTOR]->(wen:Person{name:"wen.xx"})
create (wen)-[:FRIEND]->(niu:Person{name:"超级牛"})
create (gao)-[:FRIEND]->(niu)
create (gao)-[:MENTOR]->(wei:Person{name:"wei.xx"})
create (wei)-[:MENTOR]->(:Person{name:"zhangsan"})
create (wei)-[:MENTOR]->(:Person{name:"lishi"})
create (wei)-[:FRIEND]->(:Person{name:"大牛1"})
create (wei)-[:FRIEND]->(niu2:Person{name:"大牛2"})
create (sh)-[:FRIEND]->(niu2)

1.找到gao.xx直接领导的所有人？
match (p:Person{name:"gao.xx"})-[:MENTOR]->(r) return r;

2.找到gao.xx接领导的所有人？
match (p:Person{name:"gao.xx"})-[:MENTOR*]->(r) return r;

3.找到gao.xx间接领导的所有人？
match (p:Person{name:"gao.xx"})-[:MENTOR*2..]->(r) return r;

4.gao.xx想招聘开发，于是想找到他领导的所有人的朋友？
match (p:Person{name:"gao.xx"})-[:MENTOR*]->()-[:FRIEND]->(r) return r;

5.找到wei.xx和shuang.xx的共同好友？
match (:Person{name:"wei.xx"})--(p)--(:Person{name:"shuang.xx"}) return p

6.和wen.xx有直接关系的人，不考虑方向？
match (:Person{name:"wen.xx"})-[*..1]-(p) return p;
或
match (:Person{name:"wen.xx"})-[:FRIEND|:MENTOR]-(p) return p;

7.最短路径：shuang.xx到大牛2的最短路径
match p = shortestPath((n1:Person{name:"shuang.xx"})-[*..6]-(n2:Person{name:"大牛2"})) return p;