neo4j数据库创建范例（SQL文）

SQL文：

SELECT c.id, c.name, o.amount
FROM customers c
JOIN orders o ON c.id = o.customer_id

1. 先创建节点（Table、Column）。
2. 再 MATCH 出节点，建立关系。

---

✅ 针对你的 SQL 的完整 Cypher

// -----------------------------
// 1. 创建表节点
// -----------------------------
MERGE (t_customers:Table {name: "customers"});
MERGE (t_orders:Table {name: "orders"});

// -----------------------------
// 2. 创建字段节点
// -----------------------------
MERGE (col_c_id:Column {name: "id", table: "customers"});
MERGE (col_c_name:Column {name: "name", table: "customers"});
MERGE (col_o_amount:Column {name: "amount", table: "orders"});
MERGE (col_o_customer_id:Column {name: "customer_id", table: "orders"});

// -----------------------------
// 3. 建立表-字段关系
// -----------------------------
MATCH (t_customers:Table {name: "customers"}), (col_c_id:Column {name: "id", table:"customers"})
MERGE (t_customers)-[:HAS_COLUMN]->(col_c_id);

MATCH (t_customers:Table {name: "customers"}), (col_c_name:Column {name: "name", table:"customers"})
MERGE (t_customers)-[:HAS_COLUMN]->(col_c_name);

MATCH (t_orders:Table {name: "orders"}), (col_o_amount:Column {name: "amount", table:"orders"})
MERGE (t_orders)-[:HAS_COLUMN]->(col_o_amount);

MATCH (t_orders:Table {name: "orders"}), (col_o_customer_id:Column {name: "customer_id", table:"orders"})
MERGE (t_orders)-[:HAS_COLUMN]->(col_o_customer_id);

// -----------------------------
// 4. 建立字段间 JOIN 关系
// -----------------------------
MATCH (col_c_id:Column {name:"id", table:"customers"}),
      (col_o_customer_id:Column {name:"customer_id", table:"orders"})
MERGE (col_c_id)-[:JOINS {on:"="}]->(col_o_customer_id);

---

🔍 查询验证

MATCH (t:Table)-[:HAS_COLUMN]->(c:Column)
RETURN t.name AS table, c.name AS column;

MATCH (c1:Column)-[j:JOINS]->(c2:Column)
RETURN c1.table AS table1, c1.name AS column1,
       j.on AS condition,
       c2.table AS table2, c2.name AS column2;

结果应该是：

表-字段

table      | column
-----------+------------
customers  | id
customers  | name
orders     | amount
orders     | customer_id

JOIN 关系

table1     | column1 | condition | table2 | column2
-----------+---------+-----------+--------+------------
customers  | id      | =         | orders | customer_id

---

完整的扩展方案，把 SQL JOIN 的信息 全部带进 Neo4j 的关系属性里。

---

1. SQL 信息里能提取的点

像你这句：

SELECT c.id, c.name, o.amount
FROM customers c
JOIN orders o ON c.id = o.customer_id;

可抽取出来的 JOIN 元数据：

• 关系条件 ：c.id = o.customer_id
• 连接符号 ：=
• JOIN 类型 ：INNER JOIN（省略 INNER 默认就是 INNER）
• 左表字段 ：customers.id
• 右表字段 ：orders.customer_id

---

2. 在 Neo4j 里扩展关系属性

建关系时，不只存 on:"="，而是存完整信息：

MERGE (col_c_id:Column {name:"id", table:"customers"})
MERGE (col_o_customer_id:Column {name:"customer_id", table:"orders"})
MERGE (col_c_id)-[:JOINS {
    condition: "c.id = o.customer_id",
    operator: "=",
    join_type: "INNER",
    left_table: "customers",
    left_column: "id",
    right_table: "orders",
    right_column: "customer_id"
}]->(col_o_customer_id);

---

3. 查询结果更直观

MATCH (c1:Column)-[j:JOINS]->(c2:Column)
RETURN j.join_type AS join_type,
       j.condition AS condition,
       j.left_table AS left_table,
       j.left_column AS left_column,
       j.operator AS operator,
       j.right_table AS right_table,
       j.right_column AS right_column;

结果就会是：

join_type | condition               | left_table | left_column | operator | right_table | right_column
----------+--------------------------+------------+-------------+----------+-------------+--------------
INNER     | c.id = o.customer_id    | customers  | id          | =        | orders      | customer_id

---

4. 通用做法

• condition：存完整 SQL 条件
• operator ：存 =、>、< 这种符号
• join_type ：存 INNER / LEFT / RIGHT / FULL
• left_table / right_table：存表名
• left_column / right_column：存字段名

这样以后你要还原 SQL JOIN，或者做可视化，都很方便。

---