Connect from the MongoDB Shell

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Prerequisites

Procedure
Aggregation Syntax and Short-form Syntax

This page describes how to connect to a federated database instance through the MongoDB Shell (mongosh).

Prerequisites

A federated database instance that is mapped to one or more data stores.
Note
If some or all of your data comes from an Atlas cluster, you must use MongoDB version 5.0 or greater for that cluster to take advantage of Atlas SQL.

Procedure

In Atlas, go to your federated database instance for your project.

If it's not already displayed, select the organization that contains your project from the Organizations menu in the navigation bar.
If it's not already displayed, select your project from the Projects menu in the navigation bar.
In the sidebar, click Data Federation under the Services heading.
The Data Federation page displays.

Click Connect to open the federated database instance connection modal.

Select Shell.

Install the MongoDB Shell if you haven't already.

If you do not have the MongoDB Shell installed:

Select I do not have the MongoDB Shell installed inside the connection modal.
Select your operating system from the modal dropdown menu.
Follow the installation instructions for your operating system provided in the modal.
(Optional) Confirm that your mongosh installation was successful.
To check that your installation was successful, in your terminal, run:
```
mongosh --version
```
If the installation was successful, mongosh displays a version.

If you already have the MongoDB Shell installed:

Select I have the MongoDB Shell installed inside the connection modal.
Select mongosh from the modal dropdown menu.
Note
The MongoDB Shell, or mongosh, is separate from the mongo versions in the modal dropdown menu.
If you want to ensure that you have mongosh installed, in your terminal, run:
```
mongosh --version
```
If mongosh is installed, it displays a version.

Select your authentication method.

Your authentication method depends on how your database access is configured. To learn more about database access, see Configure Database Users.

You can choose:

Password (SCRAM), or
X.509.

Atlas Data Federation provides a connection string for your authentication method.

Copy and run your connection string.

If you selected the Password (SCRAM) authentication method, you are prompted for a password for the connecting user.

(Optional) Confirm the connection to your federated database instance.

To confirm that you are connected to your federated database instance, using mongosh, run:

show dbs

If you successfully connected to your federated database instance that is mapped to a data store, mongosh displays the names of your virtual databases.

Aggregation Syntax and Short-form Syntax

Atlas SQL supports an aggregation pipeline stage syntax and a short-form syntax for constructing the SQL queries. You can use either of these syntaxes to write queries in the MongoDB Shell.

Aggregation Pipeline Stage Syntax

You can use the $sql aggregation pipeline stage to write Atlas SQL queries. See $sql for a list of properties you must provide to $sql.

The following example uses $sql syntax to execute the Atlas SQL statement select * from Users limit 2:

db.aggregate( [ {
    $sql: {
       statement: "SELECT *
                   FROM users
                   LIMIT 2",
       format: "jdbc",
       dialect: "mongosql"
   }
} ] )

Note

Atlas SQL uses the dialect mongosql.

Short-form Syntax

You can use a short-form syntax, db.sql, to supply an Atlas SQL statement directly.

Important

Short-form syntax is not stable and may change in the future.

db.sql(`
  SELECT *
  FROM users
  LIMIT 2
`);

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JDBC Driver