Question

*I have a document structured in which we embedded the salary Document into  the Employee_Detail Document.As per the MongoDb documantation ,we can use $Unwind to deconstruct the Document and use aggregated pipeline...But its not working. i am using the below script...*    
{ 
    "_id" : ObjectId("5763d4a54da83b98f269878a"),  
    "First_Name" : "fgfg", 
    "Department" : "QA", 
    "Salary" : {
        "HRA" : "1200", 
        "Basic" : "2000", 
    }

})  
And i want to get sum of basic salary based on department Like

然后预期的输出是部门Total_Basic ** QA 2000

I have used the following code to get the output. I have used the $unwind to     deconstruct the document.and use aggregated pipeline to group the department(Sum of basic Salary).

db.Employee_Detail.aggregate([
    {$unwind:"$Salary"},   {$group: {"_id": "$Department", total_Basic: {$sum: "$Salary.Basic" }
    }}
])    
But i get the below Result.   
Department    Total_Basic
QA             0

我认为$ unwind不起作用。请建议

Answer 1

您的主要问题是字段的类型Basic是一个字符串。其次，除非字段Salary包含数组，否则不需要使用unwind。

因此，请执行更新以将Basic和HRA的类型转换为浮点数，（see this stackoverflow question）

然后像这样的聚合操作会给你想要的结果：

db.Employee_Detail.aggregate([
    {$group: {"_id": "$Department", total_Basic: {$sum: "$Salary.Basic" }}
])

基于组意外行为的子文档字段的总和

1 个答案: