# How to use MongoDB Shell

how to use **MongoDB Shell (mongosh)** at the command terminal:

#### **1. Start MongoDB Shell**

If MongoDB is running, open your terminal or command prompt and type:

```sh
mongosh
```

This connects to the **local MongoDB instance** (`mongodb://localhost:27017` by default).

***

#### **2. Check the MongoDB Version**

After launching `mongosh`, you can verify the version:

```sh
db.version()
```

***

#### **3. Show Available Databases**

To list all databases:

```sh
show dbs
```

***

#### **4. Create or Switch to a Database**

To create or switch to a database (`testDB` in this case):

```sh
use testDB
```

***

#### **5. Create a Collection and Insert Documents**

Collections in MongoDB are equivalent to tables in SQL.

**Insert a Single Document**

```sh
db.users.insertOne({ name: "Alice", age: 28, city: "New York" })
```

**Insert Multiple Documents**

```sh
sdb.users.insertMan([
  { name: "Bob", age: 34, city: "Chicago" },
  { name: "Charlie", age: 29, city: "San Francisco" }
])
```

***

#### **6. Retrieve Data**

**Find All Documents**

```sh
sdb.users.find()
```

**Find a Specific Document**

```sh
db.users.findOne({ name: "Alice" })
```

**Find Documents with Filtering**

```sh
db.users.find({ age: { $gt: 30 } })  // Finds users older than 30
```

***

#### **7. Update Documents**

**Update a Single Document**

```sh
db.users.updateOne({ name: "Alice" }, { $set: { age: 29 } })
```

**Update Multiple Documents**

```sh
db.users.updateMany({ city: "Chicago" }, { $set: { city: "New York" } })
```

***

#### **8. Delete Documents**

**Delete One Document**

```sh
db.users.deleteOne({ name: "Charlie" })
```

**Delete Multiple Documents**

```sh
db.users.deleteMany({ age: { $lt: 30 } })
```

***

#### **9. Drop a Collection**

To delete the `users` collection:

```sh
db.users.drop()
```

***

#### **10. Exit MongoDB Shell**

To exit `mongosh`:

```sh
exit
```

***

#### **Final Output Example**

After executing `db.users.find().pretty()`, you might see:

```json
[
  {
    "_id": ObjectId("65ab45f12345"),
    "name": "Alice",
    "age": 29,
    "city": "New York"
  },
  {
    "_id": ObjectId("65ab45f12346"),
    "name": "Bob",
    "age": 34,
    "city": "New York"
  }
]
```

***

This example covers the **basic CRUD (Create, Read, Update, Delete)** operations in MongoDB Shell (`mongosh`). 🚀


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