Is CRUD DDL or DML operation?

Question

Is CRUD classified as DDL or DML or both. CRUD being the operation Create Read Update and Delete

Answer 1

CRUD operations when applied to an SQL database map directly to DML statements. You have to bear in mind that the "C" in CRUD corresponds to the INSERT statement in SQL which creates an instance of something in a table. There is a CREATE statement in SQL that used for DDL operations but this is not the same sense of "Create" as in CRUD.

 Create = INSERT
 Read   = SELECT
 Update = UPDATE
 Delete = DELETE

Answer 2

I'd say they're closer to Data Manipulation Language, because DDL is more about defining a schema where as DML is about working with objects within a defined schema. I propose the following map between DML and CRUD (using standard insert, create, update, delete methods from dml):

Create -- Insert Read -- Select Update -- Update Delete -- Delete

However, I don't know if thinking of it as either DDL or DML will help you very much. CRUD isn't a language so much as a set of operations for handling objects you wish to expose via some interface.