我现在看到的唯一选择就是把它分成两个查询,
第一个检查p是否连接到c:
MATCH (p:Initial{state: 'Initial', name: 'Initial'})-[:raw {person_id:'1234', type:'Encounter', code:'abcd'}]->(c:Encounter{code:'abcd', state: 'Encounter', name: 'Encounter1'}) RETURN p,c
如果上述查询返回空,则发出第二个查询以形成关系:
MATCH (p:Initial{state: 'Initial', name: 'Initial'})(c:Encounter{code:'abcd', state: 'Encounter', name: 'Encounter1'}) CREATE (p)-[:raw {person_id:'1234', type:'Encounter', code:'abcd'}]->(c)