Neo4j-Cypher查询语言-参数

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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

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Map params = new HashMap(); params.put( "id", 0 ); ExecutionResult result = engine.execute("start n=node({id}) return n.name", params );

 

节点对象参数

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Map params = new HashMap(); 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 params = new HashMap(); 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 params = new HashMap(); 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 params = new HashMap(); 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 params = new HashMap(); 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 params = new HashMap(); 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

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