HIBERNATE
16. What’s the difference between load() and get()?
| load() | get() |
| Only use the load() method if you are sure that the object exists. | Only use the load() method if you are sure that the object exists. |
| load()
method will throw an exception if the unique id is not found in the database.
|
get() method will return null if the unique id is not found
in the database.
|
| load()
just returns a proxy by default and database won’t be hit until the proxy is
first invoked.
| get()
will hit the database immediately.
|
17.What is the difference between and merge and update ?
Use update() if you are sure that the session does not
contain an already persistent instance with the same identifier, and merge() if
you want to merge your modifications at any time without consideration of the
state of the session.
18.How do you define sequence generated primary key in
hibernate?
Using <generator> tag.
Example:-
<id column="ACC_ID" name="id"
type="java.lang.Long">
<generator
class="sequence">
<param
name="table">SEQUENCE_NAME</param>
<generator>
</id>
