unwind [‘X’] as idkey1 optional match(n:corpid{corpid:idkey1}) with idkey1, [n.corpid+":"+case when n.corpname is null then ‘’ else n.corpname end] as use_code
with idkey1 ,case when use_code IS null then [] else apoc.coll.toSet(use_code) end as use_code_res
return idkey1,use_code_res ; ±----------------------+ | idkey1 | use_code_res | ±----------------------+ | “X” | [NULL] | ±----------------------+ 这里的 判断了use_code是否是空，但是最后还是返回[NULL] ，想要的结果[]