CRUD, which stands for CREATE, READ, UPDATE and DELETE, are the main functions that can be used within a Database. Different users may have different CRUD Cycles, based on the purpose of the system, e.g. A Student Database would be used to Create new Student Details, Read Existing ones, Update Student Details and Delete the details when students leave the school. In SQL, the corresponding functions are INSERT, SELECT, UPDATE and DELETE.
CRUD in Web Development
When you have a Database and you input an entry into the table, you are using the CREATE command. If you view a saved table, you are READing the data. If you then, go inside the table, and change the details inside a field of the table, you are using the UPDATE command. If the table then no longer requires a field, and you remove it, you are then using the DELETE command.
CRUD Operations can also be used with PHP.
I have added a video below, using the SELECT Statement (READ) in the Database.