# \$1dateSubtract
<a name="dateSubtract"></a>

New from version 5.0

The `$dateSubtract` aggregation operator in Amazon DocumentDB allows you to subtract a specified duration from a date value.

**Parameters**
+ `date`: A date expression that resolves to a date or timestamp.
+ `subtrahend`: A duration expression that specifies the amount of time to subtract from the `date` expression.
+ `unit`: A string that specifies the time unit for the `subtrahend` expression. Supported units are "year", "quarter", "month", "week", "day", "hour", "minute", "second", and "millisecond".

## Example (MongoDB Shell)
<a name="dateSubtract-examples"></a>

The following example demonstrates how to use the `$dateSubtract` operator to calculate the date one year ago from the current date.

**Create sample documents**

```
db.events.insertOne({
  eventName: "Player joined",
  eventTime: ISODate("2023-04-01T12:00:00Z")
});
```

**Query example**

```
db.events.aggregate([
  {
    $project: {
      eventName: 1,
      oneYearAgo: {
        $dateSubtract: {
          startDate: "$eventTime",
          amount: 1,
          unit: "year"
        }
      }
    }
  }
])
```

**Output**

```
{
  "_id" : ObjectId("64567890abcdef012345678"),
  "eventName" : "Player joined",
  "oneYearAgo" : ISODate("2022-04-01T12:00:00Z")
}
```

## Code examples
<a name="dateSubtract-code"></a>

To view a code example for using the `$dateSubtract` command, choose the tab for the language that you want to use:

------
#### [ Node.js ]

```
const { MongoClient } = require('mongodb');

async function example() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
  const db = client.db('test');
  const events = db.collection('events');

  const result = await events.aggregate([
    {
      $project: {
        eventName: 1,
        oneYearAgo: {
          $dateSubtract: {
            startDate: "$eventTime",
            amount: 1,
            unit: "year"
          }
        }
      }
    }
  ]).toArray();

  console.log(result);
  await client.close();
}

example();
```

------
#### [ Python ]

```
from pymongo import MongoClient
from bson.date_time import datetime

def example():
    client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
    db = client['test']
    events = db['events']

    result = list(events.aggregate([
        {
            '$project': {
                'eventName': 1,
                'oneYearAgo': {
                    '$dateSubtract': {
                        'startDate': '$eventTime',
                        'amount': 1,
                        'unit': 'year'
                    }
                }
            }
        }
    ]))

    print(result)
    client.close()

example()
```

------