CRUD

CRUD是指在做计算处理时的增加（Create）、查询（Retrieve）（重新得到数据）、更新（Update）和删除（Delete）几个单词的首字母简写。主要被用在描述软件系统中数据库或者持久层的基本操作功能。
In computing, CRUD is an acronym for create, retrieve, update, and delete. It is used to refer to the basic functions of a database or persistence layer in a software system.
C reate new records
R etrieve existing records
U pdate existing records
D elete existing records.