What Are CRUD Operations? :
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CRUD operations are at the heart of nearly every application you interact with. As a developer, you usually want to create data, read or retrieve data, update data, and delete data. Whether you access a database or interact with a REST API, only when all four operations are present are you able to make a complete data roundtrip in your app.
Creating, reading, updating, and deleting are so vital in software development that these methods are widely referred to as CRUD. Understanding CRUD will give you an actionable blueprint when you build applications and help you understand how the applications you use work behind the scenes. So, what exactly does CRUD mean?
Get Your Code: Click here to download the free sample code that you’ll use to learn about CRUD operations in Python.
Take the Quiz: Test your knowledge with our interactive “What Are CRUD Operations?” quiz. You’ll receive a score upon completion to help you track your learning progress:
Interactive Quiz
What Are CRUD Operations?In this quiz, you'll revisit the key concepts and techniques related to CRUD operations. These operations are fundamental to any system that interacts with a database, and understanding them is crucial for effective data management.
In Short: CRUD Stands for Create, Read, Update, and Delete
CRUD operations are the cornerstone of application functionality, touching every aspect of how apps store, retrieve, and manage data. Here’s a brief overview of the four CRUD operations:
- Create: This is about adding new entries to your database. But it’s also applicable to other types of persistent storage, such as files or networked services. When you perform a create operation, you’re initiating a journey for a new piece of data within your system.
- Read: Through reading, you retrieve or view existing database entries. This operation is as basic as checking your email or reloading a website. Every piece of information you get has been received from a database, thanks to the read operation.
- Update: Updating allows you to modify the details of data already in the database. For example, when you update a profile picture or edit a chat message. Each time, there’s an update operation at work, ensuring your new data is stored in the database.
- Delete: Deleting removes existing entries from the database. Whether you’re closing an account or removing a post, delete operations ensure that unwanted or unnecessary data can be properly discarded.
CRUD operations describe the steps that data takes from creation to deletion, regardless of what programming language you use. Every time you interact with an application, you’re likely engaging in one of the four CRUD operations.
Why Are CRUD Operations Essential?
Whether you’re working on a basic task list app or a complex e-commerce platform, CRUD operations offer a universal language for designing and manipulating data models. Knowing about CRUD as a user helps you understand what’s happening behind the curtains. As a developer, understanding CRUD provides you with a structured framework for storing data in your application with persistence:
In computer science, persistence refers to the characteristic of state of a system that outlives (persists more than) the process that created it. This is achieved in practice by storing the state as data in computer data storage. (Source)
So even when a program crashes or a user disconnects, the data is safe and can be retrieved later. This also means that the order of the operations is important. You can only read, update, or delete items that were previously created.
It’s good practice to implement each CRUD operation separately in your applications. For example, when you retrieve items, then you shouldn’t update them at the same time.
Note: An exception to this rule may be when you update a “last time retrieved” value after a read operation. Although the user performs a read CRUD operation to retrieve data, you may want to trigger an update operation in the back end to keep track of a user’s retrievals. This can be handy if you want to show the last visited posts to the user.
While CRUD describes a concept that’s independent of specific programming languages, one could argue that CRUD operations are strongly connected to SQL commands and HTTP methods.
What Are CRUD Operations in SQL?
The idea of CRUD is strongly connected with databases. That’s why it’s no surprise that CRUD operations correspond almost one-to-one with SQL commands:
| CRUD Operation | SQL Command |
|---|---|
| Create | INSERT |
| Read | SELECT |
| Update | UPDATE |
| Delete | DELETE |
When you create data, you’re using the INSERT command to add new records to a table. After creation, you may read data using SELECT. With a SELECT query, you’re asking the database to retrieve the specific pieces of information you need, whether it’s a single value, a set of records, or complex relationships between data points.
The update operation corresponds to the UPDATE command in SQL, which allows you to modify data. It lets you edit or change an existing item.
Lastly, the delete operation relates to the DELETE command. This is the digital equivalent of shredding a confidential document. With DELETE, you permanently remove an item from the database.
Writing CRUD Operations in Raw SQL
CRUD operations describe actions. That’s why it’s a good idea to pull up your sleeves and write some code to explore how CRUD operations translate into raw SQL commands.
In the examples below, you’ll use Python’s built-in sqlite3 package. SQLite is a convenient SQL library to try things out, as you’ll work with a single SQLite database file.
You’ll name the database birds.db. As the name suggests, you’ll use the database to store the names of birds you like. To keep the example small, you’ll only keep track of the bird names and give them an ID as a unique identifier.
Read the full article at https://realpython.com/crud-operations/ »
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May 29, 2024 at 07:30PM
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