Question

这是发票收集：

db.Invoice.insert({"InvoiceNo" : "1", "Total" : "22.50", "FoodId" : "1", "SupplierType" : "Meat"})
WriteResult({ "nInserted" : 1 })    
db.Invoice.insert({"InvoiceNo" : "2", "Total" : "22.50", "FoodId" : "2", "SupplierType" : "Meat"})
WriteResult({ "nInserted" : 1 })
db.Invoice.insert({"InvoiceNo" : "3", "Total" : "12.50", "FoodId" : "3", "SupplierType" : "Veg"})
WriteResult({ "nInserted" : 1 })    
db.Invoice.insert({"InvoiceNo" : "3", "Total" : "12.50", "FoodId" : "3", "SupplierType" : "Veg"})
WriteResult({ "nInserted" : 1 })    
db.Invoice.insert({"InvoiceNo" : "4", "Total" : "12.50", "FoodId" : "4", "SupplierType" : "Veg"})
WriteResult({ "nInserted" : 1 })    
db.Invoice.insert({"InvoiceNo" : "5", "Total" : "15.00", "FoodId" : "5", "SupplierType" : "Meat"})
WriteResult({ "nInserted" : 1 })    
db.Invoice.insert({"InvoiceNo" : "6", "Total" : "19.00", "FoodId" : "6", "SupplierType" : "Meat"})
WriteResult({ "nInserted" : 1 })    
db.Invoice.insert({"InvoiceNo" : "7", "Total" : "10.00", "FoodId" : "7", "SupplierType" : "Veg"})
WriteResult({ "nInserted" : 1 })    
db.Invoice.insert({"InvoiceNo" : "8", "Total" : "10.00", "FoodId" : "8", "SupplierType" : "Veg"})
WriteResult({ "nInserted" : 1 })    
db.Invoice.insert({"InvoiceNo" : "9", "Total" : "10.00", "FoodId" : "9", "SupplierType" : "Veg"})
WriteResult({ "nInserted" : 1 })   
db.Invoice.insert({"InvoiceNo" : "10", "Total" : "25.00", "FoodId" : "10", "SupplierType" : "Meat"})
WriteResult({ "nInserted" : 1 })

这是 Food Collection ：

db.Food.insert({"FoodId" : "1", "FoodType" : "Steak","BestBeforeDate" : "07/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "2", "FoodType" : "Steak","BestBeforeDate" : "07/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "3", "FoodType" : "Carrot","BestBeforeDate" : "09/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "3", "FoodType" : "Carrot","BestBeforeDate" : "17/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "4", "FoodType" : "Peas","BestBeforeDate" : "09/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "5", "FoodType" : "Ribbs","BestBeforeDate" : "05/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "6", "FoodType" : "Ribbs","BestBeforeDate" : "05/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "7", "FoodType" : "Chips","BestBeforeDate" : "30/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "8", "FoodType" : "Chips","BestBeforeDate" : "30/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "9", "FoodType" : "Chips","BestBeforeDate" : "30/05/2018",})
WriteResult({ "nInserted" : 1 })    
db.Food.insert({"FoodId" : "10", "FoodType" : "Chicken","BestBeforeDate" : "30/05/2018",})
WriteResult({ "nInserted" : 1 })

我想将总计乘以 Food Collection 的计数函数。接下来，我想计算FoodType等于“牛排”的记录数。我想将计算结果乘以发票集合中的总数。

这是我认为可行的命令：

db.Food.aggregate(
  [
    { $project: 
      { date: 1, item: 1, 
        total: { $multiply: 
          [
            {"FoodType": "Carrot"}.count(), "Total"}
          ]
        }
      }
    }
  ]
)

我想计算食物表中的牛排条目数。然后我想将结果乘以发票表中的总相应价格。

聚合。我想在mongo中计算记录，然后我想将该计数乘以不同集合中的字段

0 个答案: