The document discusses different querying techniques in Hibernate including HQL, Criteria API, native SQL, and examples of each. It provides samples of HQL queries, using named and positional parameters, executing queries to return lists or iterate through results. It also gives examples of criteria queries with restrictions, projections, ordering, examples, and native SQL queries with auto marshalling.

1. Query Session - IV

2. Different ways to express queries in Hibernate Hibernate Query Language (HQL) Criteria API for query by criteria (QBC) query by example (QBE) NativeSql using Hibernate API

3. HQL Sample HQL Query Query qry = session.createQuery("from Message"); List list = qry.list();

4. Bind Parameters in HQL Named parameters: String queryString = "from Item item where item.description like :search"; Query q = session.createQuery(queryString) .setString("search", searchString); Positional parameters: String queryString = "from Item item where item.description like ?"; Query q = session.createQuery(queryString) .setString(0, searchString);

5. Executing a Query Listing all results Ex: Query qry = session.createQuery("from Item"); List list = qry.list(); Iterating through the results Ex: Query qry = session.createQuery("from Item "); Iterator it = qry.iterate(); Scrolling with database cursors Ex: Query qry = session.createQuery("from Item "); ScrollableResults scrolRS = qry.scroll();

6. Named Query Mapping Details: <hibernate-mapping> <sql-query name=&quot;getByName&quot;> <return alias=&quot;m&quot; class=&quot;hello.Message&quot;/> SELECT {m.*} FROM MESSAGES m WHERE m.MSG_TEXT = ? </sql-query> </hibernate-mapping> Usage: Query qry = session.getNamedQuery(&quot;getByName&quot;); qry.setParameter(0, &quot;Kathir Text&quot;); List msgList = qry.list();

7. Joins in HQL An implicit association join EX: from Item i where i.bids.amount > 100 An ordinary join in the FROM clause EX: from Item i join i.bids b where i.name = 'aa' and b.amount >50 A fetch join in the FROM clause EX: from Item i left join fetch i.bids A theta-style join in the WHERE clause EX: from Item i,Message m where i.name = m.text

8. Marshalling Scalar Resultset Normal Query select i.id,i.name,b.amount from Item i join i.bids b where i.name = 'aa‘ It returns collection of object[]. Marshalling Scalar Values select new ItemBidDetail(i.id,i.name,b.amount) from Item i join i.bids b where i.name = 'aa‘ It returns collection of ItemBidDetail.

9. Criteria Sample Criteria User user = (User) session.createCriteria(User.class) .add(Restrictions.eq(&quot;email&quot;, &quot;foo@hibernate.org&quot;)) .list();

10. Few Criteria samples Sample1:- List result = session.createCriteria(Item.class) .add(Restrictions.like(&quot;description&quot;,&quot;Foo&quot;,MatchMode.ANYWHERE)) .createCriteria(&quot;bids&quot;) . add( Restrictions.gt(&quot;amount&quot;, new BigDecimal(99) ) ).list(); Sample2:- session.createCriteria(User.class) .add( Restrictions.eq(&quot;username&quot;, &quot;foo&quot;).ignoreCase() ); Sample3:- session.createCriteria(Item.class) .createAlias(&quot;bids&quot;, &quot;b&quot;) .add( Restrictions.like(&quot;description&quot;, &quot;%Foo%&quot;) ) .add( Restrictions.gt(&quot;b.amount&quot;, new BigDecimal(99) ) ); Sample4:- session.createCriteria(Item.class) .setFetchMode(&quot;bids&quot;, FetchMode.JOIN) .add( Restrictions.like(&quot;description&quot;, &quot;%Foo%&quot;) );

11. Sample5:- session.createCriteria(Item.class) .add( Restrictions.gt(&quot;endDate&quot;, new Date()) ) .setProjection( Projections.id() ); Sample6:- session.createCriteria(Item.class) .setProjection( Projections.projectionList() .add( Projections.id() ) .add( Projections.property(&quot;description&quot;) ) .add( Projections.property(&quot;initialPrice&quot;) ) ); Sample7:- Criteria cri = session.createCriteria(Bid.class) .setProjection(Projections. projectionList () .add(Projections. id ().as(&quot;bidId&quot;)) .add(Projections. property (&quot;amount&quot;).as(&quot;amount&quot;)) ) .setResultTransformer(new AliasToBeanResultTransformer(BidDetails.class) ) .addOrder(Order. asc (&quot;amount&quot;)); Few Criteria samples cont..,

12. Example Sample Example Item item = new Item(); item.setName(&quot;TV&quot;); Criteria cri = session.createCriteria(Item.class) .add(Example. create (item));

13. Native SQL Queries Auto Marshalling Sample1:- List result = session.createSQLQuery(&quot;select * from CATEGORY&quot;) .addEntity(Category.class).list(); Auto Marshalling Sample2:- session.createSQLQuery( &quot;select {i.*} from ITEM I join USERS u on i.SELLER_ID = u.USER_ID&quot; + &quot; where u.USERNAME = :uname&quot;) .addEntity(&quot;i&quot;, Item.class) .setParameter(&quot;uname&quot;, &quot;johndoe&quot;);