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What is the difference between and merge and update
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promisingram- Member Since Oct-2008 | Oct 19th, 2008
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. In other words, update() is usually the first method you would call in a fresh session, ensuring that reattachment of your detached instances is the first operation that is executed.
Thomas John
- Sep 21st, 2015
I create an object say Employee with id 1. I create this object by getting the student record from the database. Object s1 is in the session Employee e1 = null; Object o = session1.get(Employee.cl...
Mukesh Vishwakarma
- Aug 25th, 2015
Update will work at same session. After close the session or detached the state, update will not work.
But in the case of Merge after closed the session it will work. -
What is the use of cascade in hbm file?
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anupsadhwani60- Member Since Sep-2007 | Sep 16th, 2007
1) cascade="none", the default, tells Hibernate to ignore the association.
2) cascade="save-update" tells Hibernate to navigate the association when the
transaction is committed and when an object is passed to save() or
update() and save newly instantiated transient instances and persist changes to
detached instances.
3) cascade="delete" tells Hibernate to navigate the association and delete persistent
instances when an object is passed to delete().
4) cascade="all" means to cascade both save-update and delete, as well as
calls to evict and lock.
5) cascade="all-delete-orphan" means the same as cascade="all" but, in addition,
Hibernate deletes any persistent entity instance that has been removed
(dereferenced) from the association (for example, from a collection).
6) cascade="delete-orphan" Hibernate will delete any persistent entity
instance that has been removed (dereferenced) from the association (for
example, from a collection).venkat
- Jan 22nd, 2013
Using cascade property we can ensure relationship with parent to child
harikishanrao
- Dec 1st, 2010
Whenever we have a parent child relation ship, if parent record is changed then child record should also be changed. Primary key must be reflected in the child key
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Hibernate JDBC Driver
What type of JDBC driver is used in hibernate?
nabi_alam
- Mar 30th, 2012
It depends on the Database what we are using.According to the database we use corresponding Driver.
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Q1: What is the difference between Hibernate and EJB 2.1? Q2: Which one, among EJB 2.1 and Hibernate, is better?Explain with reason.Q3: When to use EJB 2.1 and when to use Hibernate? Explain with scenarios.
srinivasaraobora
- Sep 20th, 2011
Advantages of Hibernate Over EJB Entity bean is also used for object oriented view. It needs lot of things to configure for make it possible and Lot of coding need for it. After all these performance ...
sony v george
- Apr 4th, 2007
Basically Ejb and Hibenate is enterly different one But having realtion with Entitybean in Ejb and Hibernate. Entity bean is also used for object orientd view . It need lot things to configures fo mak...
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How do we create new table apart from mapping with existing table ?
CrackHead
- Aug 8th, 2011
Hibernate automatically creates new tables if there are corresponding POJOs. If you know how to write/read to/from an existing table using Hibernate, then you can easily create a table. Step#1: Creat...
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What is database persistence?How well it is implemented in Hibernate
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mani.sivapuram- Member Since May-2010 | Feb 14th, 2011
There are mainly three states in hibernate
a) Transient state
b) Persistant state
c) Detatched stateTake the employee object place the data in that object like usename, password, empid. Now the state of the object is transient state, when we write the statement given below
session.save(employeeObject);
Now the state of the object is persistent since the employee object is kept in session object then when we write the statement given below
transaction.commit();
When we apply the above statement then the employee object is going to linked with database and the data is stored in related table of that database. Since the emp object in persistent state only the data is stored in database other wise the data is not stored in database.
After the commit operation it becomes into detached state. If anybody wants to store the emp object into database then in detached state it is not possible.
mani.sivapuram
- Feb 14th, 2011
There are mainly three states in hibernate a) Transient state b) Persistant state c) Detatched state Take the employee object place the data in that object like usename, password, empid. Now th...
prasadkuppa
- Apr 24th, 2008
Preserving the data inside a database is database persistence. Persistence is once of the fundamental concepts of application developement. There are many alternatives to implement persistence. Object...
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