A brief introduction to CRUD

The four basic functions of any persistent storage system like MySQL spell CRUD:

• Create

• Read

• Update

• Delete

These are key concepts, which each of the basic MySQL commands reflect.

There is nothing technical about the words themselves, but the concepts are very important. They represent the four activities that you can expect to be able to do in every relational database system you use. There are several alternatives to this acronym and keyword series (for example, SCUD for "select, create, update, and delete" or SIDU for "select, insert, delete, and update"). The point of each of these is that database functionality boils down to two sets of opposing activities:

• Creating and deleting database objects (for example, databases, tables, records)

• Inserting and reading data (that is writing and reading)

Each of these will be addressed in the coming chapters. In this one, we start with reading data using SELECT.