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nHibernate Query


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nHibernate Query

  1. 1. nHibernate Query<br />Albert Kuo<br />
  2. 2. How nHibernation work?<br />nHibernateQuery<br />basic query<br />Restriction<br />String matcher<br />Dynamic queries<br />Subqueries<br />Using Dynamic Institation<br />Agenda<br />2<br />
  3. 3. How nHibernation work?<br />Utilize session to <br />manipulate VOs<br />Criteria<br />Session<br />tables<br />VOs<br />VOs<br />VOs<br />Configuration<br />SessionFactory<br />VOs<br />3<br />
  4. 4. How nHibernation work? – cont.<br />create<br />update<br />4<br />
  5. 5. How nHibernation work? – cont.<br />delete<br />find<br />5<br />
  6. 6. nHibernate Query<br />Criteria API<br />Hibernate Query Language<br />Object oriented querying<br />Increase compile-time syntax-checking<br />Easy to write<br />Hard to read<br />String-based querying<br />Object-Oriented SQL<br />Similar to SQL<br />Speak in terms of objects<br />Case sensitive<br />Very flexible<br />Zero compile-time syntax-checking<br />6<br />
  7. 7. Using the ICriteriainterface:<br />ICriteriacriteria = session.CreateCriteria(typeof(Cases));<br />Generate SQL statement:<br />select cases0_.caseId as caseId0_, cases0_.caseDesc as caseDesc0_, cases0_.caseTime as caseTime0_, cases0_.caseType as caseType0_, cases0_.caseAddr as caseAddr0_, cases0_.reporterStaff as reporter6_0_, cases0_.reporterPhone as reporter7_0_, cases0_.reporterAddr as reporter8_0_, cases0_.receiverStaff as receiver9_0_, cases0_.receiveTime as receive10_0_, cases0_.caseState as caseState0_, cases0_.updtDate as updtDate0_, cases0_.county as county0_, as town0_, cases0_.caseClass as caseClass0_ from Cases cases0_<br />nHibernate Query – basic query<br />7<br />
  8. 8. You usually don’t want to retrieve all instances of a class when you run a query. Instead, you want to express some constraints on the property values of your objects, so only a subset of objects is retrieved. This is called restriction.<br />nHibernate Query – Restriction<br />8<br />
  9. 9. The like operator allows wildcard searches, where the wildcard symbols are % and _<br />nHibernate Query – String matcher<br />9<br />
  10. 10. It’s common for queries to be built programmatically by combining several optional query criteria depending on user input.<br />nHibernate Query – Dynamic queries<br />10<br />
  11. 11. 11<br />
  12. 12. nHibernate Query – Subqueries<br />12<br />
  13. 13. If you find working with arrays of values a little cumbersome, NHibernate let’s you use dynamic instantiation and define a class to represent each row of results. You can do this using the HQL select new construct:<br />The custom ItemRow class doesn’t have to be a persistent class that has its own mapping file. But in order for NHibernate to “see” it, you need to import it using<br />nHibernate Query – Using Dynamic Institation<br />13<br />
  14. 14. Chapter 11. HQL: The Hibernate Query Language<br /><br />NHibernate in Action<br /><br />Reference<br />14<br />