数据库中objects,classes,associations,generalizations,aggregations是什么意思

数据库中objects,classes,associations,generalizations,aggregations是什么意思
数据库中objects,classes,associations,generalizations,aggregations是什么意思

数据库中objects,classes,associations,generalizations,aggregations是什么意思
objects：对象 classes：类 associations,：关联（表示一种关系）
generalizations：概括 aggregations：聚合（是一种函数）

objects, classes, associations, generalizations，aggregations
对象，类，关联，概括，聚合