如何使用 MERGE 创建或重用模式的一部分? [英] How to use MERGE to create or reuse a part of pattern?

问题描述

我有具有多个 REVIEW 节点的节点 PRODUCT.如果产品不存在，我将创建节点 PRODUCE，然后与 REVIEW 绑定.

I have node PRODUCT with multiple REVIEW node. I would create node PRODUCE if the product is not exist, then bind with REVIEW.

例如，我想要一个 PRODUCE 节点 {name:'X phone'} 和 3 REVIEW {content:'best phone ever'}, {content:'worst phone ever'}, {content:'nope'}.

For the example, I want a PRODUCE node {name:'X phone'} with 3 REVIEW {content:'best phone ever'}, {content:'worst phone ever'}, {content:'nope'}.

我试过了

首先，对每个 REVIEW 使用一个密码 MERGE.

First, use one cypher MERGE for each REVIEW.

MERGE(product:PRODUCT{name:'X phone'})-[:RATE]-(review:REVIEW{content:'best phone ever'})

MERGE(product:PRODUCT{name:'X phone'})-[:RATE]-(review:REVIEW{content:'worst phone ever'})

MERGE(product:PRODUCT{name:'X phone'})-[:RATE]-(review:REVIEW{content:'nope'})

它不起作用，将创建 3 个产品 {name:'X phone'}

It did not work and will create 3 PRODUCT {name:'X phone'}

我尝试使用 MERGE 来创建/重用产品，它们匹配 + 合并评论.(每条评论 2 个密码)

I tried to use MERGE to create/reuse the PRODUCT, them MATCH + MERGE the review. (2 cypher for each review)

// create/reuse PRODUCT
MERGE(product:PRODUCT{name:'X phone'})  
// create/reuse review
MATCH (product:PRODUCT{name:'X phone'}) MERGE (product)-[:RATE]-(review:REVIEW{content:'nope'})

// create/reuse PRODUCT
MERGE(product:PRODUCT{name:'X phone'})  
// create/reuse review
MATCH (product:PRODUCT{name:'X phone'}) MERGE (product)-[:RATE]-(review:REVIEW{content:'best phone ever'})

// create/reuse PRODUCT
MERGE(product:PRODUCT{name:'X phone'})  
// create/reuse review
MATCH (product:PRODUCT{name:'X phone'}) MERGE (product)-[:RATE]-(review:REVIEW{content:'worst phone ever'})

第二个解决方案有效，它只创建 1 个产品并将 3 个评论连接到该产品.但是，我必须使用两倍数量的密码.

Second solution worked, it only create 1 PRODUCT and connect 3 REVIEW to that PRODUCT. But, I have to use as twice as number of cypher.

请问有没有更好的办法解决我的问题?

I would like to ask if there is any better way for my problem ?

解决方案

我不知道我可以用 MERGE 链接 MERGE

I did not know that I can chain MERGE with MERGE

感谢@Mạnh Quyết Nguyễn 的回答，我可以为每个评论样本执行 1 个密码，链接 2 个 MERGE 子句.第一个 MERGE 如果不存在则创建产品，如果不存在则第二个 MERGE 创建评论.

thank to @Mạnh Quyết Nguyễn answer, I can do 1 cypher per review sample that chain 2 MERGE clause. First MERGE create a product if not exist, second MERGE create review if not exist.

MERGE (product:PRODUCT{name:'X phone'}) MERGE (product)-[:RATE]-(review:REVIEW{content:'worst phone ever'})

推荐答案

您随后的匹配/合并是多余的.你可以这样做:

Your subsequent match/merge is redundant. You can do:

// create/reuse PRODUCT
MERGE (product:PRODUCT {name:'X phone'})  
MERGE (product)-[:RATE]-(:REVIEW {content:'nope'})
MERGE (product)-[:RATE]-(:REVIEW {content:'best phone ever'})
MERGE (product)-[:RATE]-(:REVIEW {content:'worst phone ever'})

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