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如果返回节点具有特定类型,则执行其他匹配

cypher neo4j

lapots · 技术社区 · 6 年前

我有一个像这样的模型

推荐 cypher 查询返回关系 quest -> boots

MATCH (w:Armor)<-[:WEARS]-(p:Player)
MATCH (w)-[:PART_OF]->(set:ArmorSet)
MATCH (missing)-[:PART_OF]->(set)
MATCH (missing)<--(anything)
WHERE NOT (p)-[:WEARS]->(missing)
RETURN missing, anything

但是如何调整此查询以返回 NPC boots 任务的回报是什么?基本上我想检查节点是否为 quest 输入,然后我应该返回 npc

2 回复 | 直到 6 年前

ThirstForKnowledge 6 年前

原始答案

创建图形

CREATE
  (player:Player {name: 'Player'}),
  (shield:Armor {name: 'Shield'}),
  (armor:Armor {name: 'Armor'}),
  (gauntlets:Armor {name: 'Gauntlets'}),
  (boots:Armor {name: 'Boots'}),
  (helmet:Armor {name: 'Helmet'}),
  (dragonSet:ArmorSet {name: 'Dragon Set'}),
  (quest1:Quest {name: 'Quest I'}),
  (quest2:Quest {name: 'Quest II'}),
  (npc1:Npc {name: 'NPC I'}),
  (npc2:Npc {name: 'NPC II'}),
  (player)-[:WEARS]->(shield)-[:PART_OF]->(dragonSet),
  (player)-[:WEARS]->(armor)-[:PART_OF]->(dragonSet),
  (player)-[:WEARS]->(gauntlets)-[:PART_OF]->(dragonSet),
  (npc1)-[:PROVIDES]->(quest1)-[:REWARDS]->(boots)-[:PART_OF]->(dragonSet),
  (npc2)-[:PROVIDES]->(quest2)-[:REWARDS]->(helmet)-[:PART_OF]->(dragonSet);

第2行到第12行创建节点,而第13行到第17行建立节点之间的关系。

解决方案

MATCH
  (player:Player)-[:WEARS]->(armor:Armor)-[:PART_OF]->(dragonSet:ArmorSet),
  (missing)-[:PART_OF]->(dragonSet)
  WHERE NOT (player)-[:WEARS]->(missing:Armor)
WITH DISTINCT missing
MATCH (npc:Npc)-[:PROVIDES]->(quest:Quest)-[:REWARDS]->(missing)
RETURN npc.name AS npcName, quest.name AS questName, missing.name AS missingArmorName;

解释

第2行定义了模式“A” Player 戴 Armor ,这是 ArmorSet ".
missing 戴着失踪的帽子 “在第4行

Neo4j developers manual, WITH clauses chapter )

第6行显示已识别的缺失让我们取回 Quest 提供 Npc

结果

âââââââââââ¤ââââââââââââ¤âââââââââââââââââââ
â"npcName"â"questName"â"missingArmorName"â
âââââââââââªââââââââââââªâââââââââââââââââââ¡
â"NPC II" â"Quest II" â"Helmet"          â
âââââââââââ¼ââââââââââââ¼âââââââââââââââââââ¤
â"NPC I"  â"Quest I"  â"Boots"           â
âââââââââââ´ââââââââââââ´âââââââââââââââââââ

盔甲 探索 只是,我们必须给你们的型号加上一个标签 Monster RANDOM_DROPS .

CREATE
  (player:Player {name: 'Player'}),
  (shield:Armor {name: 'Shield'}),
  (armor:Armor {name: 'Armor'}),
  (gauntlets:Armor {name: 'Gauntlets'}),
  (boots:Armor {name: 'Boots'}),
  (helmet:Armor {name: 'Helmet'}),
  (dragonSet:ArmorSet {name: 'Dragon Set'}),
  (quest1:Quest {name: 'Quest I'}),
  (quest2:Quest {name: 'Quest II'}),
  (npc1:Npc {name: 'NPC I'}),
  (npc2:Npc {name: 'NPC II'}),
  (monster1:Monster {name: 'Monster I'}),
  (monster2:Monster {name: 'Monster II'}),
  (player)-[:WEARS]->(shield)-[:PART_OF]->(dragonSet),
  (player)-[:WEARS]->(armor)-[:PART_OF]->(dragonSet),
  (player)-[:WEARS]->(gauntlets)-[:PART_OF]->(dragonSet),
  (npc1)-[:PROVIDES]->(quest1)-[:REWARDS]->(boots)-[:PART_OF]->(dragonSet),
  (npc2)-[:PROVIDES]->(quest2)-[:REWARDS]->(helmet)-[:PART_OF]->(dragonSet),
  (monster2)-[:RANDOM_DROPS]->(boots),
  (monster1)-[:RANDOM_DROPS]->(gauntlets),
  (monster1)-[:RANDOM_DROPS]->(shield),
  (monster1)-[:RANDOM_DROPS]->(armor);

解决方案

MATCH
  (player:Player)-[:WEARS]->(armor:Armor)-[:PART_OF]->(dragonSet:ArmorSet),
  (missing)-[:PART_OF]->(dragonSet)
  WHERE NOT (player)-[:WEARS]->(missing:Armor)
WITH DISTINCT missing
MATCH (npc:Npc)-[:PROVIDES]->(quest:Quest)-[:REWARDS]->(missing)
  WHERE NOT (:Monster)-[:RANDOM_DROPS]->(missing)
RETURN npc.name AS npcName, quest.name AS questName, missing.name AS missingArmorName;

âââââââââââ¤ââââââââââââ¤âââââââââââââââââââ
â"npcName"â"questName"â"missingArmorName"â
âââââââââââªââââââââââââªâââââââââââââââââââ¡
â"NPC II" â"Quest II" â"Helmet"          â
âââââââââââ´ââââââââââââ´âââââââââââââââââââ

Tezra 6 年前

这个 coalesce Neo4j中的函数可用于压缩多个变量,以使用最相关的非空值。

MATCH (w:Armor)<-[:WEARS]-(p:Player)
MATCH (w)-[:PART_OF]->(set:ArmorSet)
MATCH (missing)-[:PART_OF]->(set)
MATCH (missing)<--(anything)
WHERE NOT (p)-[:WEARS]->(missing)
OPTIONAL MATCH (anything)<-[:GIVES]-(source)
RETURN missing, coalesce(source, anything) as source