如何解决neo4j：无效输入“唯一”的错误消息

我尝试执行此命令,但屏幕显示消息:如何解决此问题?

Invalid input 'UNIQUE': expected "(", "allShortestPaths" or "shortestPath" (line 4, column 8 (offset: 269))
"CREATE UNIQUE(s1)<-[:FROM]->(r)"

初始输入命令:

:auto USING PERIODIC COMMIT 500
load csv with headers from "https://lovecandyhsu.neocities.org/relations.csv" as csvLine
MATCH (s1:Station { id: toInteger(csvLine.fromId)}),(r:Route { id: toInt(csvLine.route_informationId)}),(s2:Station { id: toInt(csvLine.toId)})
CREATE UNIQUE(s1)<-[:FROM]->(r)
CREATE UNIQUE(r)<-[:TO]->(s2)
RETURN csvLine