CRUD

CRUD stands for Create, Read, Update, and Delete, the four fundamental operations performed on stored data. Most database-backed applications are built from these four actions.

Why it matters

CRUD is a shorthand for planning an application's data layer and its API. Each operation maps to a database statement and, in web APIs, usually to an HTTP method. Thinking in CRUD helps scope admin screens, permissions, and tests, although real applications also need searching, reporting, and business rules beyond the basics.

Example

Create  INSERT INTO users (...) VALUES (...)   POST   /users
Read    SELECT * FROM users WHERE id = 7       GET    /users/7
Update  UPDATE users SET name = ... WHERE ...  PUT    /users/7
Delete  DELETE FROM users WHERE id = 7         DELETE /users/7

Common mistakes

• Running UPDATE or DELETE without a WHERE clause, which changes every row.
• Hard deleting records that you may need to restore or audit. Soft deletes with a timestamp are common.
• Treating CRUD endpoints as the whole design and skipping validation and authorization.

Related

• SQL
• ORM
• Database transaction

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