neo4j学习笔记 （一）

一、neo4j 带参数查询

官方文档的使用方式说的很不清楚。这篇主要内容转载自http://hugh-wangp.iteye.com/blog/1848862

但是因为这篇文章来自很多年前，目前已经是新的参数语法$param，旧语法{param}已弃用，并将在以后的版本中完全删除。

Cypher支持带参数的查询，它允许开发者不需要do string building to create a query，同时它能使执行计划的缓存更容易。

 

参数可以用在WHERE子句的literals和expressions、可以用在START子句或索引查询的索引键值上、节点/关系的ID上。但是参数不能用在属性名上，因为属性是查询结构的一部分，是要编译成执行计划的。

 

参数名称只能是字母和数字的组合

 

如下是在JAVA中使用参数的几个例子：

节点ID参数

 

Map<String, Object> params = new HashMap<String, Object>();
params.put( "id", 0 );
ExecutionResult result = 
engine.execute("start n=node($id) return n.name", params );

　　

 

节点对象参数

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

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

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

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

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

Map<String, Object> params = new HashMap<String, Object>();
params.put( "s", 1 );
params.put( "l", 1 );
ExecutionResult result = engine.execute("start n=node(0,1,2) return n.name skip $s limit $l", params );

 

正则表达式参数

Map<String, Object> params = new HashMap<String, Object>();
params.put( "regex", ".*h.*" );
ExecutionResult result = engine.execute("start n=node(0,1,2) where n.name =~ $regex return n.name", params);

 二、expand_children_relationships查询语句的实现

MATCH path = (a)--(o)

WHERE id(a) = $i

with path as paths,nodes(path) as nodes

match p=(c)--(d)

where (id(d) in $id ) and c in nodes

RETURN paths,p

id为当前图的所有id