的Neo4j：複製在比賽

Question

我有Cypher支架查詢：

match(p:Product)--(stock:Stock) 
where p.StyleNumber = "Z94882A" and p.Color = "Black" and stock.Retailer = "11" 
with stock as stock, p as p 
optional match(p)-->(s:Sale) 
where s.Date = 20170801 and s.Retailer = "11" 
return p,stock, s 

在比賽中我得到重複的股票返回結果：

結果包含兩個項的尺寸：XL （見圖），因爲它有兩個銷售。但在第一個查詢中，match(p:Product)--(stock:Stock)僅返回一個產品節點，且僅附加一個庫存節點： - /。 看到這個圖來加以說明：

如果我總結的銷售和股票，我仍然得到重複的結果：

match(p:Product)--(stock:Stock) 
where p.StyleNumber = "Z94882A" and p.Color = "Black" and stock.Retailer = "11" 
with stock as stock, p as p 
optional match(p)-->(s:Sale) 
where s.Date = 20170801 and s.Retailer = "11" 
return p, sum(stock.Stockcount) as onstock, sum(s.Quantity) as sold 

爲XL其中給出：

{"Size":"XL", "Color":"Black", "Supplier":"1", "Id":"6322", "StyleNumber":"Z94882A"} 
| Stock =10 (should have been 5)  │ Sold =2 (is correct) 

問題是如何避免在這種情況下重複？

Answer 1

您需要分階段進行彙總，因爲：Stock節點獨立於Sale節點。儘早聚集，避免在它們之間創建笛卡爾產品。

match(p:Product)--(stock:Stock) 
where p.StyleNumber = "Z94882A" and p.Color = "Black" and stock.Retailer = "11" 
with sum(stock.Stockcount) as onstock, p 
optional match(p)-->(s:Sale) 
where s.Date = 20170801 and s.Retailer = "11" 
return p, onstock, sum(s.Quantity) as sold