How to Drop Databases in Redis, MongoDB, and PostgreSQL

Eric included in computer

04-06-2024 820 words 4 minutes

Contents

📚 How to Check and Delete Redis and MongoDB Data Using Docker Compose

This tutorial will guide you through the process of checking if a key exists in a Redis database, deleting it if necessary, and also how to delete data from MongoDB, all using Docker Compose commands.

🛠️ Prerequisites

Docker and Docker Compose installed
Redis and MongoDB services defined in your docker-compose.yml file

🚀 Using Docker Compose

🔴 Interacting with Redis

🔍 Check if a Key Exists

Ensure your Redis container is running by using Docker Compose:
```
docker-compose up -d
```
Connect to the Redis container using the following command:
```
docker-compose exec redis redis-cli
```
Replace redis with the name of your Redis service defined in your docker-compose.yml file.
Check if the key exists using the EXISTS command:
```
EXISTS your-key-name
```
Replace your-key-name with the actual key you want to check. The command will return 1 if the key exists and 0 if it does not.

🗝️ Check All Keys

List all keys using the KEYS command:
```
KEYS *
```
This command will return a list of all keys stored in the currently selected database.

📝 Get Key Information

Get detailed information about a specific key using the TYPE and TTL commands:
```
TYPE your-key-name
TTL your-key-name
```
- TYPE returns the data type of the key (e.g., string, list, set).
- TTL returns the remaining time to live of a key that has a timeout, or -1 if the key does not have a timeout.

🗑️ Delete a Specific Key

Delete the key using the DEL command:
```
DEL your-key-name
```

🧹 Delete All Keys

Delete all keys in the currently selected database using the FLUSHDB command:
```
FLUSHDB
```
This will remove all keys from the currently selected database.
Delete all keys in all databases using the FLUSHALL command:
```
FLUSHALL
```
This will remove all keys from all databases.

🟢 Interacting with MongoDB

🔎 Determine the Actual Name of Your Database

Ensure your MongoDB container is running by using Docker Compose:
```
docker-compose up -d
```
Connect to the MongoDB container using the following command:
```
docker-compose exec mongo mongo
```
Replace mongo with the name of your MongoDB service defined in your docker-compose.yml file.
List all databases:
```
show dbs
```
This command will display a list of all databases on your MongoDB server along with their sizes.

Example Output:
```
> show dbs
admin       0.000GB
config      0.000GB
local       0.000GB
exampleDB   0.001GB
```
In this example, exampleDB is the name of one of the databases.

📂 Select and Work with a Database

Once you know the name of your database, you can select it using the use command:

Select the database:
```
use exampleDB
```
Replace exampleDB with the actual name of your database.

📋 List Collections in a Database

After selecting the database, you can list all collections within it:

List all collections:
```
show collections
```
This will display all collections within the selected database.

Example Output:
```
users
orders
products
```

🗑️ Delete All Collections or Specific Collections

🗑️ Delete All Collections

Drop the entire database (this will delete all collections and documents within it):
```
db.dropDatabase()
```
This command will remove the entire database, including all collections and their documents.

🗑️ Delete Specific Collections

Drop a specific collection:
```
db.your-collection-name.drop()
```
Replace `your-colle…

Guide to Manage PostgreSQL Databases in Docker 🐘

This guide will help you list PostgreSQL users and databases, find your database name, and drop a PostgreSQL database within a Docker container.

Listing PostgreSQL Users and Databases

Step 1: Access the PostgreSQL Container

To access your running PostgreSQL container, use the following command. Replace your_container_name with the actual name or ID of your container.

docker exec -it your_container_name bash

Step 2: Connect to PostgreSQL

Once inside the container, connect to the PostgreSQL database using the psql command. Replace username with your PostgreSQL username (often postgres).

psql -U username

Step 3: List Users

To list all users, execute:

\du

Step 4: List All Databases

To list all databases, use:

\l

Step 5: Find Your Database Name

If you’re not sure about your database name, you can check the list of databases using the command above (\l). Look for the name in the output.

Step 6: Exit

To exit the psql prompt, type:

\q

Then, exit the container:

exit

Dropping a PostgreSQL Database 💔

Step 1: Access the PostgreSQL Container

If you are not already inside the container, access it using the same command as before:

docker exec -it your_container_name bash

Step 2: Connect to PostgreSQL

Connect to PostgreSQL using:

psql -U username

Step 3: Drop the Database

After connecting, you can drop the database by executing the following command. Replace zilean with the name of the database you want to drop.

DROP DATABASE zilean;

Step 4: Exit

To exit the psql prompt, type:

\q

Then, exit the container:

exit

Summary 🌟

This guide provided instructions on how to list PostgreSQL users and databases, find your database name, and drop a PostgreSQL database within a Docker container. Ensure you have the necessary permissions and always back up your data before performing destructive operations.