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Suppose that you are given a collection of JSON documents that represent a database of multiple...

Suppose that you are given a collection of JSON documents that represent a database of multiple choice exams taken by students. Write mongoDB queries to answer the following questions:

1. Determine the total number of exams.

The following json file is only an example to illustrate what the data looks like. The actual data has unique optionid and questionid.

{ name:’Smith’, id:159008743, courseId:’198:111’, semester:’Sp2018’, examNumber:1, totalQuestions:10, totalCorrect:8, percentage:0.8, grade:’B’, date_submitted:’04-25-2018’, time_submitted:’19:25:24’, room:’Hill 363’, computerNumber:5, ip:’198.253.128.5’, questions:[ { number:1, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false }, { option:’B’, 1 optionid:384734, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384249, optiontext:’Option C’, correct:true, answered:true },{ option:’D’, optionid:3834223, optiontext:’Option D’, correct:false, answered:false }] },{ number:2, questionid:34325, questiontext:’Question 2’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, 2 optionid:384729, optiontext:’Option D’, correct:true, answered:true }] },{ number:3, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:true, answered:true },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false }] },{ number:4, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, 3 optionid:384729, optiontext:’Option A’, correct:true, answered:true },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false }] },{ number:5, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, 4 optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:true, answered:true }] },{ number:6, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:true, answered:true },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false }] }, 5 { number:7, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:true },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:true, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false }] },{ number:8, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false },{ option:’B’, 6 optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:true, answered:true }] },{ number:9, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:true, answered:true },{ option:’D’, 7 optionid:384729, optiontext:’Option D’, correct:false, answered:false } ] }, { number:10, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:true, answered:false }, { option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false }, { option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:true }, { option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false } ] } ] } 8

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Answer #1

> db.mycol.insert({ name:’Smith’, id:159008743, courseId:’198:111’, semester:’Sp2018’, examNumber:1, totalQuestions:10, totalCorrect:8, percentage:0.8, grade:’B’, date_submitted:’04-25-2018’, time_submitted:’19:25:24’, room:’Hill 363’, computerNumber:5, ip:’198.253.128.5’, questions:[ { number:1, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false }, { option:’B’, 1 optionid:384734, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384249, optiontext:’Option C’, correct:true, answered:true },{ option:’D’, optionid:3834223, optiontext:’Option D’, correct:false, answered:false }] },{ number:2, questionid:34325, questiontext:’Question 2’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, 2 optionid:384729, optiontext:’Option D’, correct:true, answered:true }] },{ number:3, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:true, answered:true },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false }] },{ number:4, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, 3 optionid:384729, optiontext:’Option A’, correct:true, answered:true },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false }] },{ number:5, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, 4 optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:true, answered:true }] },{ number:6, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:true, answered:true },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false }] }, 5 { number:7, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:true },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:true, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false }] },{ number:8, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false },{ option:’B’, 6 optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:false },{ option:’D’, optionid:384729, optiontext:’Option D’, correct:true, answered:true }] },{ number:9, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:false, answered:false },{ option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false },{ option:’C’, optionid:384729, optiontext:’Option C’, correct:true, answered:true },{ option:’D’, 7 optionid:384729, optiontext:’Option D’, correct:false, answered:false } ] }, { number:10, questionid:34532, questiontext:’Question 1’, answers:[ { option:’A’, optionid:384729, optiontext:’Option A’, correct:true, answered:false }, { option:’B’, optionid:384729, optiontext:’Option B’, correct:false, answered:false }, { option:’C’, optionid:384729, optiontext:’Option C’, correct:false, answered:true }, { option:’D’, optionid:384729, optiontext:’Option D’, correct:false, answered:false } ] } ] })
WriteResult({ "nInserted" : 1 })
>db.mycol.aggregate([{$group : {_id : "$name", total_exam : {$sum : 1}}}])
{ "_id" : 'Smith', "total_exam" : 1 }

Explanation:

$group operator will creates group on the basis of name fields

$sum will keep on adding 1 to the sum of all entries obtained having similar name and hence counting the number of exams given by a student.

Note:[Please comment in case of any query]

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