This time is the association of One-Many. The first is a class diagram: a table structure, and the relationship between MANY-ONE. Create Table EMP (SSN Char (10) Primary Key, Dep_name VARCHAR (255)) Create Table Dep (Name Varchar (255) Primary Key Map File Content: -> Interpretation: 1. This time EMPLOYEES is a collection type, is information defining the set element. It should be noted that the column = "dep_name" here is the column of the Employee class, which is associated with the table of the Department class. 2. DEP_NAME is only used to do associated column, so it cannot be accessed by Employee, which is invisible to the point of view of the object model.
