neo4j query cypher utterance

Neo4j Query Cypher Statement
Recently, the nosql database neo4j has been used, and the cypher statement has been used for its comprehensive query learning.

Sharing summary:

1. According to the index as nePort, fuzzy query all nodes for id. Sort by id, limit only goes to the first 10 records
start n = node:nePort('id:*')  
match (x)-[:NE_PORT]->(n)
return n,x
order by n.id limit 10


2 .This query is much more than 1 query, match matches the relationship between nodes, first obtains it according to the index query, starting point n, in the matching relationship, [: relationship name], a->b means from a to b.
This query, Is to obtain the existence of a node relationship ambition n, and the relationship is NE_PORT, the starting point x
start n = node:nePort('id:*')  
match (x)-[:NE_PORT]->n
return n.type,n.id ,n.speedId,n.code,n.name,n.optical,n.used,n.serial,x.id
order by n.id skip 0 limit 10; 3If

the fuzzy query node id attribute contains 11, the node.
START ne=node: ne('id=*11*') return ne

4. Match all subordinates [:VC*]
START ne=node(4106557) MACTH ne-[:NE_PORT]->port-[:VC*] -vc where vc.vtag=0 RETURN vc; 

5. Only the nodes whose layer 2 relationship is VC are matched.
START ne=node(4106557) MATCH ne-[:NE_PORT]->port-[:VC*1..2]->vc WITH vc WHERE vc.vtag? = 0 RETURN vc;

6. Conditions, fuzzy query. Query label contains NEs in Zhongshan  
start n=node(3) match n-[:NE]-ne where ne.label =~ '.*Zhongshan.*' return ne.id, ne.label, ne.name;


Query Syntax (Cyphe Query Language)
neo4j's own graph-based search algorithm implements a set of query language parsing and provides some common aggregation functions (max, sum, min, count, etc.).

Ø START: The starting point in the graph, obtained by element ID or so search.

Ø MATCH: The matching mode of the graph, bound to the starting point.

Ø WHERE: filter condition.

Ø RETURN: Return what is required.

Syntax example:



Join query:
start n=(1) match (n)-[:BLOCKS]->(x) return x

Where condition:
start n=(2, 1) where (n.age < 30 and n.name = "Tobias") or not(n.name = "Tobias") return nAggregate

function:
start n=(2,3,4) return avg(n.property)

Order:
start n=(1,2,3) return n order by n.name DESC

pagination:
start n=(1,2,3,4,5) return n order by n.name skip 1 limit 2
START n=node( *) return n skip 1 limit 2
count:
START n=node(*) RETURN count(*);
START n=node(*) RETURN "Hello Graph with "+count(*)+" Nodes!" as welcome;

start n = node:nePort('id:*') return n skip " + pageNo + " limit " + pageSize;

the following are a few examples of using parameters in JAVA:
node ID parameter
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Map<String, Object> params = new HashMap<String, Object>();
params.put( "id", 0 );
ExecutionResult result =  
engine.execute("start n=node({id}) return n.name", params );

node object Parameters
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Map<String, Object> params = new HashMap<String, Object>();
params.put( "node", andreasNode );
ExecutionResult result = 
engine.execute("start n=node({node}) return n.name", params );

多节点ID参数
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Map<String, Object> params = new HashMap<String, Object>();
params.put( "id", Arrays.asList( 0, 1, 2 ) );
ExecutionResult result = 
engine.execute("start n=node({id}) return n.name", params );
字符串参数
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Map<String, Object> params = new HashMap<String, Object>();
params.put( "name", "Johan" );
ExecutionResult result =
engine.execute("start n=node(0,1,2) where n.name = {name} return n", params );
索引键值参数
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Map<String, Object> params = new HashMap<String, Object>();
params.put( "key", "name" );
params.put( "value", "Michaela" );
ExecutionResult result =
engine.execute("start n=node:people({key} = {value}) return n", params );

索引查询参数
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Map<String, Object> params = new HashMap<String, Object>();
params.put( "query", "name:Andreas" );
ExecutionResult result = 
engine.execute("start n=node:people({query}) return n", params );

SKIP和LIMIT的数字参数
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Map<String,Object> params = new HashMap<String, Object>();
) The node named A in the RETURN n index will be returned. Result: call example: db = new ImpermanentGraphDatabase();


































engine = new ExecutionEngine( db );
CypherParser parser = new CypherParser();
ExecutionEngine engine = new ExecutionEngine(db);
Query query = parser.parse( "start n=(0) where 1=1 return n" );
ExecutionResult result = engine.execute( query );
assertThat( result.columns(), hasItem( "n" ) );
Iterator<Node> n_column = result.columnAs( "n" );
assertThat( asIterable( n_column ), hasItem(db.getNodeById(0)) );
assertThat( result.toString(), containsString("Node[0]") );