java persistence with hibernate second edition

java face test-persistence layer 10 91, what is ORM.Object-Relational mapping (object-relational Mapping, or ORM) is a technique to solve the problem of mismatch between the object-oriented model of program and database; To put it simply, ORM is to automatically persist objects in a program to relational databases or to convert rows from relational database tables into

performance, and we can analyze it through the statement log of the database service. Many o/rm can automatically generate table schema (automatically generate tables) based on mapping instructions, but we should not do so, especially in production environments or products, remember that we should design our own tables. If the table design is poor, it is your fault, not o/rm. Java Persistence API There are

(){Return username;}... Now let's take a look at how to create a ing to the license. This is a multi-to-many (manyto) relationship, of course, that is, @ manytomany. @ Manytomany (mappedby = "users ")Public list Return licences;}...} Here we use the mappedby parameter to point to the user attribute of the licence class. This allows the persistence engine to use the @ jointable specified in the licence. This is the entity. Now we turn to the topic of

statements are provided at the same time, joined employs data integrity restrictions. This strategy is fine as long as you don't use a basic type of polymorphic query or @onetomany Association. Its real function is to correlate the polymorphic @manytoone supported by the policy pattern on the data access layer.You should avoid using table_per_class because it does not generate a valid SQL statement.9. The size of the persistence contextWhen using JPA

development can save a lot of code, improve efficiency. But Hibernate's disadvantage is that the learning threshold is high, mastering the threshold is higher, and how to design the O/R mapping, how to trade off between performance and object models, and how to use hibernate with great experience and ability.In short, in accordance with the needs of users in a limited resource environment as long as the maintenance and extensibility of a good softwar

Criticizing the Java persistence framework The original article is well written. For details, see http://fromapitosolution.blogspot.com/2008/12/criticism-of-java-persistence.html. The brief translation is as follows:Most applicationsProgramThey are all data-driven and need to be able to access tables and modify data. Although the

. Hibernate can be used in any situation where JDBC is used. It can be used in Java client programs or Servlet/JSP web applications. The most revolutionary is that, hibernate can replace CMP in the J2EE architecture of application EJB to fulfill the task of data persistence. From the Baidu business card above, we can s

/79134612 what is the difference between clearing and clearing sessions? Session clearing cache refers to synchronously updating the database according to the changes in the state of the objects in the cache. (Hibernate includes three types of session Flush mode) Clearing is to clear some or all objects of the session or disable the session; Http://blog.sina.com.cn/s/blog_62a151be0100nf28.html13. How does Hibernat