Create, read, update and delete: Difference between revisions

Revision as of 23:13, 18 July 2023

Revision as of 10:30, 11 October 2023

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Together these four operations make up the basic operations of storage management known as CRUD: ''Create'', ''Read'', ''Update'' and ''Delete''.

== DatabasesUse cases ==

=== Databases ===

The acronym CRUD refers to the major operations which are implemented by [[database]]s. Each letter in the acronym can be mapped to a standard [[SQL|Structured Query Language (SQL)]] statement.<ref>{{cite web|url=https://www.educative.io/blog/crud-operations|title=CRUD operations explained: Create, read, update, delete|author=Maryam Sulemani|date=7 April 2021|access-date=14 December 2021}}</ref>

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Some [[big data]] systems do not implement UPDATE, but have only a timestamped INSERT (journaling), storing a completely new version of the object each time.

=== RESTful APIs ===

The acronym CRUD also appears in the discussion of [[Representational state transfer|RESTful APIs]]. Each letter in the acronym may be mapped to a [[HTTP method|Hypertext Transfer Protocol (HTTP) method]]:

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In HTTP, the GET (read), PUT (create and update), POST (create - if we don't have `id` or `uuid`), and DELETE (delete) methods are CRUD operations as they have storage management semantics, meaning that they let [[user agent]]s directly manipulate the states of target [[Web resource|resources]].<ref>{{cite web |url=https://tools.ietf.org/html/rfc7231#section-4 |title=Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content, Section 4 |last=Fielding |first=Roy |date=June 2014 |website=IETF |publisher=Internet Engineering Task Force (IETF) |access-date=2018-02-14 |rfc=7231}}</ref> The [[Hypertext Transfer Protocol#Request methods|POST]] method, on the other hand, is a process operation that has target-resource-specific semantics which typically exceed the scope of CRUD operations.<ref name="it-is-okay-to-use-post">{{cite web|url=https://roy.gbiv.com/untangled/2009/it-is-okay-to-use-post |title=It is okay to use POST |author=Roy T. Fielding |publisher=roy.gbiv.com |date=2009-03-20 |access-date=2020-04-14 |quote=POST only becomes an issue when it is used in a situation for which some other method is ideally suited: e.g., retrieval of information that should be a representation of some resource (GET), complete replacement of a representation (PUT), or any of the other standardized methods that tell intermediaries something more valuable than “this may change something.” The other methods are more valuable to intermediaries because they say something about how failures can be automatically handled and how intermediate caches can optimize their behavior. POST does not have those characteristics, but that doesn’t mean we can live without it. POST serves many useful purposes in HTTP, including the general purpose of “this action isn’t worth standardizing.”}}</ref>

=== User Interface ===

{{original research|section=yes|date=November 2018}}