MongoDB query operators:

#programming #mongodb

This past few months, I have spent time learning the back-end technologies and how they are working. In this journey, I discovered MongoDB,which is flexible and allows developers to quickly store large amounts of unstructured data.

So today we are going to learn how to write MongoDB queries such as:

CRUD Operations:

Create: insertOne(), insertMany()
Read: findOne(), find()
Update: updateOne(), update()
Delete: deleteOne(), deleteMany()

More advanced query operations using:

Comparison query operators : $gt , $lt , $gte , $lte
Set Operators: $in, $all, $nin

let's get started

Create operations:

Those Create or Insert operations give us the ability to add a new document to a collection. We can use:

insertOne: inserts a single document into a collection.
insertMany: inserts multiple documents into a collection.

Read Operations:

We use those operations to get data from our MongoDB database. We can use these methods:

find: This method is called on the collection you’d like to query.
findOne: This method is used to retrieve a single document from a collection.

Update Operations:

With Update operations, we can modify existing documents or documents in a collection. Let’s go through the update methods:

updateOne: This method is used to update a single document.
updateMany: This method is used to update multiple documents.

Consider the following:

Delete Operations:

The deleteOne() and deleteMany() methods are used to remove documents from a collection. Let’s see how these methods work:

deleteOne: This method is used to delete a single document in a collection.
deleteMany: This method is used to delete multiple documents in a collection

Comparison Query Operators:

These are tools to locate the requested data in a database. So we use, $lt, $lte, $gt, and $gte set of operators to achieve this. Let’s look at them individually:

$gt: Match if the requested value is "greater than" the value provided in the query;
$gte: Match if the requested value is "greater than or equal to" the value provided in the query;
$lt: Match if the requested value is "less than" the value provided in the query;
$lte: Match if the requested value is "less than or equal to" the value provided in the query;

Set Operators:

Set operators includes $in, $nin, and $all. These query operators take a list of one or more values. Let’s look at them individually:

$in: This operator will return a document if any of the given values matches the search field. If the field holds an array, the $in operator will return all the documents in a collection where at least one of the given values matches the search field.
$nin: $nin (not in) returns a document only when none of the given elements matches the search field.
$all: $all matches if all the given elements match the search key.

I learned a lot during these few months, and I hope you did learn a thing or two from reading this.

Please let me know if there's anything wrong with this article. I would love to correct and improve it.