How to select a single field for all documents in a MongoDB collection?

Question

In my MongoDB, I have a student collection with 10 records having fields name and roll. One record of this collection is:

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Answer 1

get all data from table

db.student.find({})

SELECT * FROM student

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get all data from table without _id

db.student.find({}, {_id:0})

SELECT name, roll FROM student

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get all data from one field with _id

db.student.find({}, {roll:1})

SELECT id, roll FROM student

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get all data from one field without _id

db.student.find({}, {roll:1, _id:0})

SELECT roll FROM student

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find specified data using where clause

db.student.find({roll: 80})

SELECT * FROM students WHERE roll = '80'

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find a data using where clause and greater than condition

db.student.find({ "roll": { $gt: 70 }}) // $gt is greater than 

SELECT * FROM student WHERE roll > '70'

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find a data using where clause and greater than or equal to condition

db.student.find({ "roll": { $gte: 70 }}) // $gte is greater than or equal

SELECT * FROM student WHERE roll >= '70'

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find a data using where clause and less than or equal to condition

db.student.find({ "roll": { $lte: 70 }}) // $lte is less than or equal

SELECT * FROM student WHERE roll <= '70'

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find a data using where clause and less than to condition

db.student.find({ "roll": { $lt: 70 }})  // $lt is less than

SELECT * FROM student WHERE roll < '70'

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