Most Useful MongoDB Queries

Insert, insertOne, find, findOne, field filtering, project --*Create and Read Operation*

1. insert

insert using insert query we can add a single data to the MongoDB database . But now insert is deprecated. Instead of insert we have to use insertOne query and for adding multiple data we can use insertMany([])

2. insertOne

Using insertOne query we can add a new document to our Database.

Example:

db.test.insertOne({ name: 'shourav' , age: 23})

3. insertMany

Using insertMany query we can add multiple document at a time in our DB. We have to insert data in an array formate in this query.

Example:

db.test.insertMany([{name: 'Pallab Krishna Das', age:25}, {name: 'Ashim Krishna Das', age:22}])

4. find

By using find query we can get all document of our Database. And you also can set finding rules here for getting data and getting specific parts of a document.

Example:

// To Get all data of a data collection of database 
db.test.find()

// To Get all data that match with the provided value / values
db.test.find({age: 23})

// To Get all data that match with the provided value / values and The document Field we want to get. (Field Filtering)
db.test.find({age: 23}, {name: 1, age: 1, email: 1, phone})


// 

5. findOne --*Read Operation*

By using findOne query we can get one document form our DB that match with the provided document.

Example:

// This query will find one document which age is 23
db.test.findOne({age: 23})

// This query will find one document with age is 23 and The document Field we want to get (Field Filtering)
db.test.findOne({age:23}, {name:1, age: 1})

6. field filtering --*Read Operation*

When we explicitly define which field we need in the find request output it's called field filtering

Example:

// only give name, age and email filed form all fields
db.test.find({age: 17}, {name:1, age:1, email: 1})

// only give name, age filed form all fields
db.test.findOne({age:23}, {name:1, age: 1})

7. project --*Read Operation*

We can use project method for field filtering in find query. The project does'nt work on findOne query

Example:

// Field Filtering with project
db.test.find({gender: female}).project({name: 1, email: 1, gender: 1})

$eq, $ne, $gt, $lt, $gte, $lte --*Read Operation*

8. $eq

$eq is a comparison operator , it's means $eq ---> equal to . We can compare value using this operator. Which value is equal to this condition will be get.

Example:

// This query will give only the document which age is equal to 12

db.test.find({age: {$eq: 12}}, {name: 1, gender: 1, age: 1})

9. $ne

$ne is a comparison operator, it's means $ne ---> not equal to. We can compare value using this operator. Which value is not equal to this condition will be get/displayed or rendered.

Example:

// This query will give only the document which age is not equal to 12

db.test.find({age: {$ne: 12}}, {name: 1, gender: 1, age: 1})

10. gt

gt means greater than.

Example:

// This query will give the document/documents which age is greater than 24
db.test.find({age: {$gt: 24}}, {name: 1, gender: 1, age: 1})

11. gte

gte means greater than equal

Example:

// This query will give the document / documents which age is greater then and equal 25
db.test.find({ age: {$gte: 25}}, {name:1, gender: 1, age: 1})

12. lt

lt means less than.

Example:

// This query will give the document/documents which age is less than 24
db.test.find({age: {$lt: 24}}, {name: 1, gender: 1, age: 1})

13. lte

lte means less than equal

Example:

// This query will give the document / documents which age is less then and equal 25
db.test.find({ age: {$lte: 25}}, {name:1, gender: 1, age: 1})

$in, $nin, implicit and condition --*Read Operation*

14. implicit and

যখন আমরা একই field এর ভিতরে , coma ব্যবহার করে একাধিক condition / value add করা হয় তখন implicit and বলে ।

Example:

// { $gte: 18, $lte: 30 } is implicit and
db.test.find({ age: { $gte: 18, $lte: 30 } }, { age: 1 })

// { gender: 'Female', age: { $gte: 18, $lte: 30 } } these gender and age also implicit and type
db.test.find({ gender: 'Female', age: { $gte: 18, $lte: 30 } })

15. sort

Using sort query we can sort document based on a value.

Example:

// Here we are sorting data based on age
db.test.find({ age: { $gte: 18, $lte: 30 } }, { age: 1 }).sort({age:1})

16. in

Using in operator we can get document if the any of the value of the filed match with value array.

Example:

// This is the example of `in` operator
db.test.find({ gender: "Female" , age: {$in : [18, 20, 22, 24, 26, 28, 30]} }, { age: 1, gender: 1})

17. nin

Using nin operator we can get document if the any of the value of the filed do not match with value array.

Example:

// This is an example of `nin` operator
db.test.find({ gender: "Female" , age: {$nin : [18, 20, 22, 24, 26, 28, 30]} }, { age: 1, gender: 1})

explicit $and, $or operator --*Read Operation*

18. $and

যখন আমরা $and operator ব্যাবহার করে নিজে থেকে বলে দেই একাধিক condition / value হবে সেটাকে বলা হয় explicit and.

Example:

 // Explicit `$and` operator / সব গুলো ভ্যালু থাকতে হবে। 
 db.test.find({
     $and : [
     {gender: 'Female'},
     {age: {$ne: 15}},
     {age: {$lte: 30}}
     ]
     
 }).project({age: 1, gender:1,  email:1})

19. $or

$or operator ব্যাবহার করে বলে দেওয়া হয় যে কোন একটি Value থাকলেই document টি নিয়ে আসবে।

Example:

 // Explicit `$or` operator / যেকোন একটি value থাকলেই হবে। 
db.test.find({
    $or: [
     {"skills.name" : 'JAVASCRIPT'},
     {"skills.name" : 'PYTHON'}
     
    ]
    
}).project({age: 1, skills: 1}).sort({ age:1 })
   

20. implicit or using in query

Example:

 // Implicit or operator / যেকোন একটি value থাকলেই হবে। 
db.test.find({
    "skills.name": {$in: ['JAVASCRIPT', 'PYTHON']}
    
}).project({age: 1, skills: 1}).sort({ age:1 })
   

$exists, $type, $size --*Read Operation*

21. $exists

কোন field সব গুলো document এর মধ্যে আছে কি না $exists ব্যাবহার করে আমরা দেখতে পারি । $exists এর value boolean দিতে হয়।

Example:

// যে সব document এ age field আছে সেগুলো দেখাবে
db.test.find({age: {$exists: true}})

// যে সব document এ phone field নেই সেগুলো দেখাবে
db.test.find({phone: {$exists: false}}) 

/* Note: exists ব্যাবহার করলে field থাকলেই result এ document টা দেখাবে সেক্ষেত্র field এর value null, undefined, empty, empty string,
 empty array, empty object যাই হোক না কেন */

22. $type

$type ব্যবহার করে field এর value type বলে দেওয়া হয়। Type মিলে গেলে সেই document টা দেখাবে।

Example:

db.test.find({friends: {$type: 'array'}}, {name: 1, age: 1})

23. $size

$size is an array method. একটি array এর মধ্যে কত গুলো element আছে তা জানা যায় এই $size এর ব্যাবহার করে।

Example:

// size এর value যা দেওয়া হবে Query করে তত গুলো element ওয়ালা document গুলো নিয়ে আসবে। 
db.test.find({ friends: { $size: 4 } }).project({ friends: 1 })

array value, $all , $elemMatch --*Read Operation*

24. array vale syntax such as arrayName: "value"

For reading specific array value we can use arrayName: "value" syntax

Example:

// সব Document এর মধ্যে যে গুলোর interests array এর মধ্যে Cooking ভ্যালু আছে সব গুলো দেখাবে
db.test.find({interests: "Cooking"}).project({interests: 1})

25. array index syntax such as "arrayName.index": "value", "friends.0": "Shourav" , "friends.2": "Niloy"

Example:

// এখানে যে সব document এর interests array এর 3rd index এর ভ্যালু "Cooking" সেগুলো দেখাবে। 
db.test.find({"interests.2": "Cooking"}).project({interests: 1})

25. array index and value exactly match

Example:

// এখানে যে সব document এর interests array এর value [ "Gardening", "Gaming", "Cooking" ] সেগুলই দেখাবে
db.test.find({interests: [ "Gardening", "Gaming", "Cooking" ]}).project({interests: 1})

/* ----Note: এই Syntax এ শুধু ভ্যালু গুলো থাকলেই হবে না তাদের index ও একই হতে হবে। ------  */

26. $all

$all array query syntax accepts an array of value and It returns all the document matches the values

Example:

/* 
এখানে যে সব document এর interests array এর value ["Gardening", "Gaming"] আছে সব গুলো দেখাবে
যদি কোন document এ  interests array এর value এর ২ টার বাইরে আরো থাকে তাহলেও দেখাবে। মূলত এই ২ টি থাকলেই হবে। 
Same to same match হতে হবে না। 
*/
db.test.find({ interests: {$all: ["Gardening", "Gaming"]}}).project({interests: 1})

26. $elemMatch object syntax

$elemMatch Query ব্যাবহার করে object এর ভিতরে থেকে নির্দিষ্ট ভ্যালু আছে সে সব document বের করা যায়

Example:

db.test.find({skills: {$elemMatch: {name: "JAVASCRIPT", level: "Intermidiate"}}}, {skills: 1})

$set, $addToSet, each, $push *Update Operations*

27. $set

$set using this query we can update a document value. But it has a problem , it works nicely in primitive data type but in the not primitive data type like array , object this query totally replace all values. We can use it in array , object type for entirely change the object.

Example:

db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    { $set: {age: 99} } )

28. $addToSet

Using $addToSet Query we can add an element or multiple element into an array of a document. It used for document update.

Example:

// Here Friends is an array , we are updating the document . adding `Krishna` to the friends array.
db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    {
        $addToSet: {
            friends: "Krishna"
        }
    }

)

29. $addToSet and $each Queries

Using $each query with the $addToSet query we can add multiple elements in a array at a time. But it ignore the duplicate value. If an array element already exist and we want to add the same element using $addToSet then it will do not add again.

Example:

(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    {
        $addToSet: {
            friends: {$each: ['Krishna', 'Gouranggo', 'Nittanondo']}
        }
    }

)

30. $push

Using $push we can do same operation like $addToSet. But there is more with $push , $addToSet doesn't allow adding duplicate element but using $push we can add same element multiple times in an array.

Example:

(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    {
        $push: {
            friends: {$each: ['Krishna', 'Gouranggo', 'Nittanondo']}
        }
    }

)

$unset, $pop, $pull, $pullAll --*Delete Operations*

31. $unset

Using $unset query we can delete / remove property form document

Example:

db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    { $unset: { age: 1 }}
    )

32. $pop

Using $pop query we can remove array last and first element.

Example:

// For Removing Array Last Element
db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    { $pop: { skills: 1 }}
    )

// For Removing Array First Element

db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    { $unset: { skills: -1 } }
    )

33. $pull

Using $pull query we can remove specific element of an array using it's value or condition

Example:

// For remove cooking from interests array "interests" : [ "Cooking" "Writing", "Reading" ]`
db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    { $pull: { interests: "Cooking" } }
)

// Array after pull: "interests" : [ "Writing", "Reading" ]

34. $pullAll

Using $pullAll query we can remove multiple document from an array.

Example:

db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065") },
    { $pullAll: { languages: ["Catalan", "German"] } }
)

// It will remove "Catalan", "German" element form languages array

More about $set, set in object --*Update Operation*

35. $set for object and array of object

Using $set we can also update / Replace object and array of object's value

Syntax: arrayName.$.objectPropertyName: "newValue"

Note: [$ symbol is mandator here. It grab the first match one.]

Example:

db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065"), "name.lastName": 'Datta' },
    { $set:{ "education.$.major": 'SSC'}}
    
)

36. $inc

Using this query we can increase a number filed value

Example:

db.test.updateOne(
    { _id: ObjectId("6406ad63fc13ae5a40000065"), "name.lastName": 'Datta'},
    {$inc: {age: 5}}
    )

// Now it will increase age 5 years

delete documents, drop collection --*Delete Operation*

37. deleteOne

For deleting a document

Example:

db.test.deleteOne({_id : ObjectId("6406ad64fc13ae5a4000008a"),})

38. delete collection

For deleting a Data Base collection

Syntax: db.<collectionName>.drop( { writeConcern: { w: 1 } } ) Example:

db.extraTest.drop( { writeConcern: { w: 1 } } )