CRUD

Create, read, update and delete

In computer programming, create, read, update and delete (CRUD) are the four basic functions of persistent storage. Sometimes CRUD is expanded with the words retrieve instead of read, modify instead of update, or destroy instead of delete. It is also sometimes used to describe user interface conventions that facilitate viewing, searching, and changing information; often using computer-based forms and reports.

The term was likely first popularized by James Martin in his 1983 book Managing the Data-base Environment. The acronym may be extended to CRUDL to cover listing of large data sets which bring additional complexity such as pagination when the data sets are too large to hold easily in memory.

Another variation of CRUD is BREAD, an acronym for "Browse, Read, Edit, Add, Delete".

Database applications

The acronym CRUD refers to all of the major functions that are implemented in relational database applications. Each letter in the acronym can map to a standard SQL statement and HTTP method:

Operation	SQL	HTTP
Create	INSERT	POST
Read (Retrieve)	SELECT	GET
Update (Modify)	UPDATE	PUT / PATCH
Delete (Destroy)	DELETE	DELETE

Making full use of HTTP methods, along with other constraints, is considered "RESTful".
Although a relational database provides a common persistence layer in software applications, numerous other persistence layers exist. CRUD functionality can be implemented with an object database, an XML database, flat text files, custom file formats, tape, or card. 

User interface

CRUD is also relevant at the user interface level of most applications. The software must allow the user to:

• Create or add new entries
• Read, retrieve, search, or view existing entries
• Update or edit existing entries
• Delete/deactivate existing entries

Without at least these four operations, the software cannot be considered complete. Because these operations are so fundamental, they are often documented and described under one comprehensive heading, such as "contact management", "content management" or "contact maintenance" (or "document management" in general, depending on the basic storage unit for the particular application).