Neo4j 实战（二）-- neo4j 基础语句

前言：

  这篇本章通过 neo4j 官方给出的 movie graph 例子学习 neo4j 基本的创建、查询、修改、删除语句。

一、创建图谱

1. 获取 Example Graph - Movie Graph 实例

 2. 导入官网的图谱创建语句

 下面展示了电影 "The Matrix" 的人物信息与关系：

// create the profiles of actors
CREATE (TheMatrix:Movie {title:'The Matrix', released:1999, tagline:'Welcome to the Real World'})
CREATE (Keanu:Person {name:'Keanu Reeves', born:1964})
CREATE (Carrie:Person {name:'Carrie-Anne Moss', born:1967})
CREATE (Laurence:Person {name:'Laurence Fishburne', born:1961})
CREATE (Hugo:Person {name:'Hugo Weaving', born:1960})
CREATE (LillyW:Person {name:'Lilly Wachowski', born:1967})
CREATE (LanaW:Person {name:'Lana Wachowski', born:1965})
CREATE (JoelS:Person {name:'Joel Silver', born:1952})

//create the relationships between the roles and actors
CREATE
(Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrix),
(Carrie)-[:ACTED_IN {roles:['Trinity']}]->(TheMatrix),
(Laurence)-[:ACTED_IN {roles:['Morpheus']}]->(TheMatrix),
(Hugo)-[:ACTED_IN {roles:['Agent Smith']}]->(TheMatrix),
(LillyW)-[:DIRECTED]->(TheMatrix),
(LanaW)-[:DIRECTED]->(TheMatrix),
(JoelS)-[:PRODUCED]->(TheMatrix)

CREATE (Emil:Person {name:"Emil Eifrem", born:1978})
CREATE (Emil)-[:ACTED_IN {roles:["Emil"]}]->(TheMatrix)

 导入成功!

 汤姆·汉克斯参演的电影

 二、查询语句

1. 按名字查找某个实体 

eg1: Find the actor named "Tom Hanks"...

 neo4j $ MATCH (tom {name: "Tom Hanks"}) RETURN tom 

 eg2: Find the movie with title "Cloud Atlas"...

 neo4j $ MATCH (cloudAtlas {title: "Cloud Atlas"}) RETURN cloudAtlas 

2. 使用 limit 关键字限制查询实体个数

eg: Find 10 people...

 neo4j $ MATCH (people:Person) RETURN people.name LIMIT 10 

3. 使用 where 条件查询语句

eg: Find movies released in the 1990s...

neo4j $ MATCH (nineties:Movie) 
　　　　 WHERE nineties.released >= 1990 AND nineties.released < 2000
　　　　 RETURN nineties.title

4. 已知一节点和关系查找另一节点信息

eg1: List all Tom Hanks movies...

neo4j $ MATCH (tom:Person {name: "Tom Hanks"})-[:ACTED_IN]->(tomHanksMovies) 
　　　　 RETURN tom,tomHanksMovies 

 eg2: Who directed "Cloud Atlas"?

 neo4j $ MATCH (directors)-[:DIRECTED]->(cloudAtlas {title: "Cloud Atlas"}) 
　　　　　 RETURN directors.name 

 or

 neo4j $ MATCH (cloudAtlas {title: "Cloud Atlas"})<-[:DIRECTED]-(directors) 
　　　　　 RETURN directors.name

5. 查询某个节点上以同样关系连接的节点信息

eg: Tom Hanks' co-actors...

neo4j $ MATCH (tom:Person {name:"Tom Hanks"})-[:ACTED_IN]->(m)<-[:ACTED_IN]-(coActors) 
　　　　 RETURN coActors.name

 6. 查询与某结点有关系的所有结点信息

eg: How people are related to "Cloud Atlas"...

 neo4j $ MATCH (people:Person)-[relatedTo]-(:Movie {title: "Cloud Atlas"}) 
　　　    RETURN people.name, Type(relatedTo), relatedTo

7. 查找两个节点的最短路径（不论任何关系）

eg: Bacon path, the shortest path of any relationships to Meg Ryan

 neo4j $ MATCH p=shortestPath( (bacon:Person {name:"Kevin Bacon"})-[*]-(meg:Person {name:"Meg Ryan"}))
　　　　  RETURN p 

 8. 查询两个结点的中介结点信息

eg: Find someone to introduce Tom Hanks to Tom Cruise

neo4j $ MATCH (tom:Person {name:"Tom Hanks"})-[:ACTED_IN]->(m)<-[:ACTED_IN]-(coActors),
  　　　(coActors)-[:ACTED_IN]->(m2)<-[:ACTED_IN]-(cruise:Person {name:"Tom Cruise"})
　　　　 RETURN tom, m, coActors, m2, cruise

9. 删除所有结点及关系

 neo4j $ MATCH (n) DETACH DELETE n or

 neo4j $ MATCH (n)-[m] DELETE n, m 

三、总结

1. 查询一般格式：(keyword  、variable 、  entity or relationship)

 MATCH (sub:subject)-[pre:predicate]->(obj:object) RETURN sub, pre, obj 

2. 如果是单向关系需要注意箭头方向