CRUD, an acronym for Create, Read, Update, and Delete, represents the fundamental operations performed on data in databases or other persistent storage systems. These operations are foundational to most modern software systems.
With the advent of REST [1], CRUD [2] has become central to the design of
APIs. RESTful APIs typically map HTTP methods [3, 4]
POST (Create), GET (Read),
PUT (Update), and DELETE (Delete) to these operations.
The Create operation refers to the generation and initial storage of new data. This includes collecting data from diverse sources, synthesizing new information, and organizing it into a structured, consistent format suitable for storage and retrieval.
The Read operation involves retrieving and accessing existing data. It encompasses querying data sources, extracting relevant information, and interpreting the results without modifying the underlying data.
The Update operation refers to the modification of existing data. This may involve correcting inaccuracies, augmenting data with new information, or removing obsolete elements, ensuring the data remains accurate and relevant over time.
The Delete operation involves the permanent or temporary removal of data. This includes data erasure, archival for long-term storage, or marking records as inactive, depending on system requirements and data retention policies.
The List operation, often considered an extension of Read, involves retrieving a collection of related data entries. It includes sorting, filtering, and structuring data for presentation, enabling users or systems to navigate large datasets effectively.
CRUD analysis is a systematic approach to understanding how data interacts with system operations. It reveals what data is required, how it is manipulated, and how it flows within the system.
This section outlines a CRUD analysis for a simple blog system that does not include comments. The focus is on the core entities and their CRUD operations, which are essential for managing posts, authors, categories, and media.
The blog system will manage the following core entities:
The following table summarizes the CRUD operations for each entity in the blog system:
| Entity | Create | Read | Update | Delete |
|---|---|---|---|---|
| Post | Author creates new post | View published posts | Edit content or metadata | Remove post |
| Author | Register account | Display profile and posts | Update bio/profile | Remove account |
| Category/Tag | Create new tags/categories | Filter/search by tag | Rename/reassign | Delete unused categories |
| Media | Upload media files | Display with posts | Replace/reupload | Delete media |
| User (optional) | Register user | Access profile or dashboard | Update password or preferences | Delete account |
If the blog uses a RESTful API, CRUD operations can be mapped to HTTP methods as follows:
| Operation | HTTP Method | Example Endpoint |
|---|---|---|
| Create | POST |
/posts, /authors |
| Read | GET |
/posts/{id}, /categories |
| Update | PUT or PATCH |
/posts/{id}, /authors/{id} |
| Delete | DELETE |
/posts/{id}, /media/{id} |
The following table summarizes the CRUD operations for each entity in the blog system:
| Resource | Create | Read | Update | Delete |
|---|---|---|---|---|
| Post | ✓ | ✓ | ✓ | ✓ |
| Author | ✓ | ✓ | ✓ | ✓ |
| Category/Tag | ✓ | ✓ | ✓ | ✓ |
| Media | ✓ | ✓ | ✓ | ✓ |
| User (optional) | ✓ | ✓ | ✓ | ✓ |