Aggregation framework to get the name of students with test one score less than the total average of all the tests

For this, you can use aggregate(). We have considered test records as “Value1”, “Value2”, etc. Let us create a collection with documents −

> db.demo432.insertOne(
...    {
...       "_id" : 101,
...       "Name" : "David",
...       "Value1" : 67,
...       "Value2" : 87,
...       "Value3" : 78
...    }
... )
{ "acknowledged" : true, "insertedId" : 101 }
> db.demo432.insertOne(
...    {
...       "_id" : 102,
...       "Name" : "Sam",
...       "Value1" : 98,
...       "Value2" : 45,
...       "Value3" : 90
...    }
... )
{ "acknowledged" : true, "insertedId" : 102 }

Display all documents from a collection with the help of find() method −

> db.demo432.find();

This will produce the following output −

{ "_id" : 101, "Name" : "David", "Value1" : 67, "Value2" : 87, "Value3" : 78 }
{ "_id" : 102, "Name" : "Sam", "Value1" : 98, "Value2" : 45, "Value3" : 90 }

Following is the query to get the name of students with test one score to be less than average of all the tests −

> db.demo432.aggregate([{
...    $project: {
...       Name: '$Name',
...       Value1: '$Value1',
...       average: {
...          $avg: ['$Value1', '$Value2', '$Value3']
...          }
...       }
...    },
...    {
...    $group: {
...       _id: null,
...       NameValue1: {
...          $push: {
...             "Name": "$Name",
...             "Value1": "$Value1"
...          }
...       },
...       totalAverage: {
...          $avg: '$average'
...          }
...       }
...    },
...    { $project:
...    { lessthanAverageNames:
...    {
...       $map:
...       {
...          input: {
...             $filter: {
...                input: "$NameValue1",
...                as: "out",
...                cond: {
...                   $lt: ["$$out.Value1", "$totalAverage"]
...                   }
...                }
...             },
...             as: "o",
...             in: "$$o.Name"
...             }
...          }
...       }
...    }
... ]);

This will produce the following output −

{ "_id" : null, "lessthanAverageNames" : [ "David" ] }

AmitDiwan

Updated on 03-Apr-2020 14:15:06

• Related Questions & Answers
• Get the average of an entire field using the aggregation framework in MongoDB?
• How to sum the score of students with the same name in MySQL with ORDER BY?
• Find out the records of students with more than a specific score in MySQL?
• Python program to find average score of each students from dictionary of scores
• Get Absolute value with MongoDB aggregation framework?
• C++ program to check how many students have greater score than first one
• MongoDB query to get average in aggregation of array element?
• What do you mean by a Framework? Name the types of framework available.
• Get the average of marks in MongoDB with aggregate?
• How to print all students name having percentage more than 70% in JavaScript?
• Get the Average of Average in a single MySQL row?
• C# Program to get the name of the drive
• MongoDB aggregation framework to sort by length of array?
• Averaging a total from a Score column in MySQL with the count of distinct ids?
• MongoDB aggregation framework with group query example?