In **Redis**, **hash tables** allow for efficient storage of data as structures that represent **associative arrays** or **objects**, making them ideal for storing objects with multiple fields.

**Redis** itself can be considered a **hash table** since it has **string keys** and corresponding **values**, which can be of various **data types**.

# Key Commands for Working with Hash Tables

**Redis** provides **several** commands for working with **hash tables**, which can be **grouped based** on their purpose: for **setting**, **getting**, and **manipulating** data within hashes.

To begin with, to **set** or **update** values in a hash, use the `HSET` **command**:

This **command** adds or updates the `name` **field** in the **hash** with the **key** `user:1000`. To **retrieve** the **value** of a **field**, use the `HGET` **command**:

It **returns** the **value** of the `name` **field** from the `user:1000` **hash**. If you need to work with **multiple fields**, use `HGETALL` to get all **key-value pairs** from the **hash**:

This will **return** all **fields** and their **values** from the **hash**. You can also **retrieve** only the **values** of the **fields** using `HVALS`, or to get only the **keys**, use the `HKEYS` **command**:

When you need to **delete** one or more **fields** from a **hash**, use the `HDEL` **command**:

This **deletes** the `name` **field** from the `user:1000` **hash**. After **deleting** a **field**, if you need to **check** whether a **specific field** exists, use the `HEXISTS` **command**:

It **returns** `1` if the **field** exists, and `0` if it doesn't. If you need to **change** a **numeric field** (for example, **incrementing** its **value**), use the `HINCRBY` **command**:

This **command** increments the **age field** by `1`. Finally, to get the **number** of **fields** in a **hash**, use the `HLEN` **command**:

This will **return** the **number** of **fields** in the `user:1000` **hash**.

Which command is used to retrieve all fields and values of a hash in Redis?

Which command should be used to delete a field from a hash in Redis?

This course will introduce you to the fundamentals of Redis and its use in real-world applications. We'll cover key Redis commands, data types, key expiration and transactions, as well as how to integrate Redis with Spring for efficient data caching.

This section provides an introduction to Redis, highlighting its core features and common use cases. You’ll learn how to install Redis on different platforms, including Windows and macOS, and get familiar with the basics of connecting to and starting the Redis server.

Here, we explore the essential Redis commands for managing and manipulating data effectively. You'll learn how to set, retrieve, increment, and delete data using commands like SET, GET, EXISTS, INCR, DECR, and tackle practical tasks to apply these concepts in real-world scenarios.

Here, you will learn about key Redis data types, including Lists, Sets, Sorted Sets, and Hashes. You will explore their functionality and practical applications through focused exercises designed to reinforce your understanding of each data type.

You'll explore advanced features of Redis, including managing key lifecycles, executing transactions, and leveraging the Pub/Sub messaging system. Additionally, you'll learn essential security practices to safeguard your Redis environment against unauthorized access.

This section introduces the fundamentals of caching and demonstrates how to configure Redis as a cache in a Spring application. It covers key caching annotations and practical examples of caching queries in web applications, concluding with a summary of the main concepts.

Introduction to Redis

Hash Table

Key Commands for Working with Hash Tables

1. Which command is used to retrieve all fields and values of a hash in Redis?

2. Which command should be used to delete a field from a hash in Redis?