Neo4j 图数据库入门（二）：一篇搞定 Cypher 增删改查——在电影社交网络里从 0 建到删

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CREATE (p:Person {name: '张三', age: 30, gender: '男'})
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RETURN p;

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CREATE (m:Movie {title: '流浪地球', year: 2019, rating: 7.9})
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RETURN m;
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CREATE (c:Company {name: '中影股份', founded: 1999})
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RETURN c;

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CREATE
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  (p1:Person {name: '李四', age: 28}),
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  (p2:Person {name: '王五', age: 35}),
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  (p3:Person {name: '赵六', age: 26}),
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  (m1:Movie {title: '三体', year: 2023, rating: 8.5}),
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  (m2:Movie {title: '满江红', year: 2023, rating: 7.0}),
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  (c1:Company {name: '光线传媒', founded: 1998});

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MATCH (a:Person {name: '张三'}), (b:Person {name: '李四'})
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CREATE (a)-[:KNOWS {since: 2018}]->(b)
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RETURN a, b;

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// 好友链：李四 → 王五 → 赵六，以及张三 → 王五
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MATCH (a:Person {name: '李四'}), (b:Person {name: '王五'})
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CREATE (a)-[:KNOWS {since: 2020}]->(b);
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MATCH (a:Person {name: '王五'}), (b:Person {name: '赵六'})
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CREATE (a)-[:KNOWS {since: 2021}]->(b);
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MATCH (a:Person {name: '张三'}), (b:Person {name: '王五'})
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CREATE (a)-[:KNOWS {since: 2019}]->(b);

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MATCH (p:Person {name: '赵六'})
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CREATE (p)-[:ACTED_IN {role: '配角', year: 2023}]->(m:Movie {title: '孤注一掷', year: 2023, rating: 6.9})
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RETURN p, m;

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// 所有人物
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MATCH (p:Person) RETURN p;
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// 只取电影的部分属性（返回表格而不是节点）
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MATCH (m:Movie) RETURN m.title, m.year, m.rating;
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// 精确匹配一个人物
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MATCH (p:Person {name: '张三'}) RETURN p;

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// 张三认识谁？
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MATCH (:Person {name: '张三'})-[:KNOWS]->(friend:Person)
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RETURN friend.name;
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// 谁导演了流浪地球？（箭头方向反过来）
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MATCH (director:Person)-[:DIRECTED]->(:Movie {title: '流浪地球'})
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RETURN director.name;
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// 张三出演的电影，以及关系上的角色属性
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MATCH (:Person {name: '张三'})-[r:ACTED_IN]->(m:Movie)
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RETURN m.title, r.role, r.year;

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// 张三的朋友的朋友（2 跳）
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MATCH (:Person {name: '张三'})-[:KNOWS]->()-[:KNOWS]->(fof:Person)
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RETURN DISTINCT fof.name;

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MATCH (:Person {name: '张三'})-[:KNOWS*1..3]->(contact:Person)
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RETURN DISTINCT contact.name;

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// 张三到赵六之间的所有路径
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MATCH path = (:Person {name: '张三'})-[:KNOWS*]->(:Person {name: '赵六'})
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RETURN path;
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// 最短路径（跨关系类型，* 不指定类型即任意关系）
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MATCH path = shortestPath(
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  (:Person {name: '张三'})-[*]-(:Person {name: '赵六'})
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)
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RETURN path;

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// 与张三有 KNOWS 关系的所有人（不区分谁认识谁）
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MATCH (:Person {name: '张三'})-[:KNOWS]-(other:Person)
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RETURN other.name;

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// 改一个属性
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MATCH (p:Person {name: '张三'})
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SET p.age = 31
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RETURN p;
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// 改多个属性
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MATCH (p:Person {name: '张三'})
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SET p.age = 31, p.email = 'zhangsan@example.com'
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RETURN p;
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// += 合并属性：只新增/覆盖列出的键，其余保留
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MATCH (p:Person {name: '张三'})
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SET p += {city: '北京', hobby: '跑步'}
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RETURN p;

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// 给张三加一个 Actor 标签
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MATCH (p:Person {name: '张三'})
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SET p:Actor
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RETURN p;
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// 再删掉
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MATCH (p:Person {name: '张三'})
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REMOVE p:Actor
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RETURN p;

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MATCH (p:Person {name: '张三'})
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REMOVE p.email
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RETURN p;

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// 删掉张三和李四之间的 KNOWS 关系
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MATCH (:Person {name: '张三'})-[r:KNOWS]->(:Person {name: '李四'})
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DELETE r;

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MATCH (p:Person {name: '赵六'})
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DELETE p;

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MATCH (p:Person {name: '赵六'})
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DETACH DELETE p;

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// 危险操作！删除所有节点和关系
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MATCH (n) DETACH DELETE n;