csv - Neo4j 密码 : MERGE conditionally with values from LOAD CSV

Question

我正在尝试从 CSV 导入，其中有些行有帐号，有些则没有。如果帐户确实有号码，我想使用它们进行合并:会有一些记录，其中帐户的名称已更改，但号码将始终保持不变。对于没有帐号的其他记录，我能做的最好的就是合并帐户名称。

所以我真的需要某种条件:如果一行有帐号，则合并该帐号，否则合并帐号名称。类似...

LOAD CSV WITH HEADERS FROM 'file:///testfile.csv' AS line
MERGE (x:Thing {
  CASE line.accountNumber WHEN NULL
    THEN name: line.accountName
    ELSE number: line.accountNumber
  END
})
ON CREATE SET
x.name = line.accountName,
x.number = line.accountNumber

但这当然行不通。有什么想法吗？

Answer 1

要在 LOAD CSV 中测试 .csv 文件中的“NULL”值，您必须测试空字符串。

测试文件.csv

acct_name,acct_num
John,1
Stacey,2
Alice,
Bob,4

这假设帐户名称是唯一的...

LOAD CSV WITH HEADERS FROM 'file:///testfile.csv' AS line

// If acct_num is not null, merge on account number and set name if node is created instead of found.
FOREACH(number IN (CASE WHEN line.acct_num <> "" THEN [TOINT(line.acct_num)] ELSE [] END) |
    MERGE (x:Thing {number:number})
    ON CREATE SET x.name = line.acct_name
)

// If acct_num is null, merge on account name. This node will not have an account number if it is created instead of matched.
FOREACH(name IN (CASE WHEN line.acct_num = "" THEN [line.acct_name] ELSE [] END) |
    MERGE (x:Thing {name:name})
)