实践Neo4j之七Cypher

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Cypher

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基本格式：
()-[]-()
([identifier][:label][{map-construct}])-[[identifier]:relationShipType[|relationShipType][*n..m]]-([identifier][:label])
(): 代表node(s)
[]: 代表relationShip
-,->,<-: direction
identifier：标识符或变量，可选，如果不指定，则表示anonymous，当指定时，()可省略
label: node的lable，可选，支持多个，例如：(a:User:Admin)
*n..m: 设定关系层次，可选，默认*1，表示一层关系，例如：[:KNOWS*2..5]、[:KNOWS*0..1]、[:KNOWS*..5]、[:KNOWS*]
{map-construct}: 属性过滤，例如：(a {name: 'Andres', sport: 'Brazilian Ju-Jitsu'})

node(s) lookup by ID

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start user=node(1) return user;
start user=node(1,3) return user;

node(s) lookup using an index

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//users is index name
start john=node:users(name = "John Johnson") return john
//native Luence query
start john=node:users("name:John Johnson") return john
//native Luence query
start john=node:users("name:John* AND yearOfBirth<1980") return john

//automatice indexing
start john=node:node_auto_index(name = "John Johnson") return john

//schema indexing, USER is a label
match (john:USER) where john.name='John Johnson' return john

getting the results

return nodes, properties, relationship, path and paging.

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MATCH (s1:Station)-[r:connected]-(s2:Station)
WHERE s1.name="Euston"
RETURN DISTINCT r.line

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ExecutionEngine engine = new ExecutionEngine(graphDb);
String cql = "start user=node(1)" + " match (user)-[:HAS_SEEN]->(movie)" + " return movie;";
ExecutionResult result = engine.execute(cql);
for(Map<String,Object> row : result){
	System.out.println("Row:" + row);
}

create

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//create node
create newuser{
	name: 'Grace Spencer',
	yearOfBirth: 1982,
	email: 'grace@mycompany.com'
}
return newuser;

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start john = node:users(name = "John Johnson"), grace = node(10)
//create relationship
create john-[r:IS_FRIEND_OF]->grace
return r;

delete

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start grace = node(10)
delete grace

update

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start john=node:users(name = "John Johnson")
set john.yearOfBirth = 1973

aggregation

聚合

function

函数

piping using the with clause

管道

cypher compatibility

cypher兼容性