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Date is a common field in most databases, and sometimes we need to find exact documents from a collection in MongoDB. For example, if we have a collection of orders, we might search for those documents before or after a specific date.

In this article, we will see how to compare dates in MongoDB. Also, we will see a relevant example and explanation to make the topic easier to understand.

Comparing Dates in MongoDB

In order to find any particular document in a collection, we have to use find()a built-in method in MongoDB called . This method will retrieve a specific document by the conditions we specify.

We will then use ISODate()the method to select a date.

In the following example, we will see how to compare two fields in MongoDB. First, let's insert some documents into our collection.

db.order.insertMany( [
   { _id: 0, type: "Product A", OrderDate: new ISODate("2021-05-18T14:11:30Z") },
   { _id: 1, type: "Product B", OrderDate: new ISODate("2020-03-20T11:31:05Z") },
   { _id: 2, type: "Product C", OrderDate: new ISODate("2020-01-15T06:32:15Z") }
] )

Now let's retrieve only this data after the date 2021-02-22T10:03:46.000Z. The command for this is shown below.

db.order.find( { OrderDate: { $gt: ISODate("2021-02-22T10:03:46.000Z") } } )

In the above command, $gtis a comparison operator (greater than). You can use some other comparison operators if necessary.

Comparison operators available in MongoDB

Shared below are the available comparison operators, which can be used for aggregation in MongoDB.

• $eq − This stands for the equality operator.
• $ne − This represents the not equal to operator.
• $gt − This stands for greater than operator.
• $gte − This stands for greater than or equal to operator.
• $lt − This stands for the less than operator.
• $lte − This stands for less than or equal to operator.
• $in − This matches any value in the array.
• $nin - This does not match any value in the array.

Now, after executing the above command, you will get the following result output in the console:

{ _id: 0,
  type: 'Product A',
  OrderDate: 2021-05-18T14:11:30.000Z }

请注意, the commands in this article are for MongoDB database and must be run on the MongoDB console.