hibernate learning

One of the cores of hibernate: use the object relation to map the set algebraic relational
database :
             1. There is a table structure.
             2. There are N columns in each row of data on the table, and the data on the N columns has a type.
             3. There are associated fields between each table as the existence of an association relationship.
             4. . . . .

Java class: object type relationship
             1. There is a class exists
             2. Each instance object of a class has M class attributes, and M class attributes have type
             3. There may be references to other classes in each class.
             4. . . . .
It can be seen from the above that there is a similar relationship between java classes and database tables. Java classes
and .
       The above only knows that this kind of mapping can be established. If you have a more specific understanding, just look at the hibernate mapping
file . This is an xml file that describes the mapping. Of course, some mappings are now implemented
in , we have to see them in the mapping entity class. Here I still focus on the xml mapping file to learn. Look at the nodes in the xml
file, what does each node mean. You can know
the .

             1.DOCTYPE information
                DTD information.
             2.hibernate-mapping
                has shema, loading strategy (lazy or non-lazy, etc.), package and other information
             3.class
                 has a lot of information about tabl attributes and update strategies, and configuration information for data loading.
                 Such as table properties, name properties, dynamic-update properties, lazy and so on.
             4.id
                 defines the mapping of attributes to the primary key of the database table.
                  1.generator sub-element: used to generate a unique identifier for the instance of the persistent class.
                  2. Different identifier generators.
             5.composite-id
                   defines multiple attributes to the joint primary key.
             6.property
                   defines the persistent properties of javabean style.
             7.many-to-one
                    defines a common association with another persistent class. Typically a foreign key refers to the primary key of the target table.
             8. one-to-one
                    One-to-one relationship.
             9.. . . . . . .
TODO