to sum up:
Table corresponding to the class name, attribute name corresponding to the field name
java: many to many: each class attributes add a set of the other class
Many: to add a property of one of a set of classes of the other, a number of other properties to add one class
One: each class add a property of the other class
Table: many to many: establishing an intermediate table, the intermediate table contains two foreign keys, the other two are the primary key table
Many: establishing a multi-party multi-field as a foreign key in another table
One: optionally establish one field as a foreign key in another table
Contact between the table is established through the outer primary bond (the foreign key: the primary key of another table)