Hibernate-4

6.Query languages

Q-A)Why we need a query language in hibernate.
  • for join quires.
  • for update PK.

  • JPQL queries can use in HQL,But HQL queries cant use JPQL.
  • SQL queries cant use in JPQL & JPQL  queries cant use in SQL.
  1. SQL include all DDL,DML quires.
  2. But JPQL & HQL include DML quires.
  3. JPQL include UPDATE,DELETE,SELECT quires.
  4. HQL include UPDATE,DELETE,SELECT,INSERT INTO... SELECT quires. 

NH Vs JPAH differences in session vs entity manager

                Should be considered:-(R):return type
                                                   :-(Q):query language

1.Get data
CreateQuery vs CreateQuery
(R)Query/TypeQuery vs Query/TypeQuery
(Q)JPQL/HQL vs JPQL(Cant use for the SQL)

2.List of data
list() vs getResultList()


3.UniqueResult(0 vs getSingleResult()

4.addEntity vs <not define>

5.getNameQuery  vs createNamedQuery

6.getNamedNativeQuery Vs CreateNameQuery

Parameters
Using mixture of these parameters is no not a good practice
a)Positional Parameters
use number as parameter
use "?" to represent
Must be positive integer
Gap between 2 parameters should be always 1
Do not want to start 1 (can start like 50,51,52)

b)Named Parameters
use text for represent  parameters.
use ":" to represent

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