How hibernate is retrieved

how hibernate is retrieved
How to retrieve ( Query method )
Navigation Object Graph retrieval method: Navigating to other objects based on objects that have already been loaded
Customer customer = (customer) session.get (customer.class,1);
customer.getorders ();//obtain a customer's order
oid Retrieval Method: Retrieving objects by the OID of the object
get ()/load (); method to retrieve.
HQL Retrieval Method: Using object-oriented HQL query Language
query query = session.createquery ("HQL");
QBC Retrieval Method: Use the QBC (query by Criteria) API to retrieve objects. This API encapsulates query statements based on string literals and provides a more object-oriented query interface.
Criteria = Session.createcriteria (customer.class);
local SQL Retrieval method: SQL query statement using local database
sqlquery query = Session.createsqlquery ("SQL");
HQL
hql:hibernate Query Language
Features: Object-oriented query, support method chain programming
1. Querying All Records　　

list<customer> list = Session.createquery ("from Customer"). List ();  for (Customer customer:list) {System.out.println (customer);}

　　2. Use aliases for queries

// using aliases, alias as can be omitted List<customer> list =session.createquery ("from Customer C"). List (); SYSTEM.OUT.PRINTLN (list); // using aliases: with parameters list<Customer> list = Session.createquery ("from Customer as C where c.cname =?"). SetString (0, "Xiao Shen"). List (); SYSTEM.OUT.PRINTLN (list); // The select * from customer notation is not supported. You can write a select alias from the customer as alias; list<customer> list = Session.createquery ("Select C from Customer C"). List (); SYSTEM.OUT.PRINTLN (list);

　　3. Sorting

list<customer> list = session.createquery ("from Customer C order by c.id Desc"). List ();  for (Customer customer:list) {System.out.println (customer);}

　　4. Paging Query

Query query = Session.createquery ("from Order"); Query.setfirstresult(10); Query.setmaxresults ); List<Order> list = query.list ();  for (Order order:list) {System.out.println (order);}

　　5. Single Object query

Customer customer = (Customer) Session.createquery ("from customer where CNAME =?") ). SetString (0, "Xiaoming"). Uniqueresult (); SYSTEM.OUT.PRINTLN (customer);

　　6. Parameter binding

//1. Bind using the Sign methodQuery query = Session.createquery ("from Customer where cname =?")); Query.setstring (0, "Xiao Shen"); List<Customer> list =query.list (); SYSTEM.OUT.PRINTLN (list); Query Query= Session.createquery ("from Customer where cname =?") and CID =? "); Query.setstring (0, "Xiao Shen"); Query.setinteger (1,3); List<Customer> list =query.list (); SYSTEM.OUT.PRINTLN (list);
//2. Binding with a nameQuery query = Session.createquery ("From Customer where Cname=:name and Cid=:id"); Query.setstring ("Name", "Xiao Shen"); Query.setinteger ("ID", 3); List<Customer> list =query.list (); SYSTEM.OUT.PRINTLN (list);//3. Binding Entitieslist<order> list =Session.createquery ("From Order o where O.customer =?"). Setentity (0, customer). List (); for(Order order:list) {System.out.println (order);}

　　7. Projection operation

// Query the name of the customer list<object> list = Session.createquery ("Select C.cname from Customer C"). List (); SYSTEM.OUT.PRINTLN (list); // Check two properties list<object[]> list = Session.createquery ("Select C.cid,c.cname from Customer C"). List ();  for (object[] objects:list) {System.out.println (Arrays.tostring (objects));} // need to provide the appropriate construction method list<customer> list = Session.createquery ("Select New Customer (CNAME) from Customer"). List (); SYSTEM.OUT.PRINTLN (list);

　　8. Fuzzy Query

Query query = Session.createquery ("From Customer where cname is like?") ); Query.setparameter (0, "small%"); List<Customer> list = query.list (); SYSTEM.OUT.PRINTLN (list);    

　　9. Aggregation function

Long Count = (long) session.createquery ("SELECT count (*) from Order"). Uniqueresult (); System.out.println (count);    

　　10. Name the query (configure the query statement in the configuration file)

list<customer> list = Session.getnamedquery ("FindAll"). List (); SYSTEM.OUT.PRINTLN (list);

SQL Multi-table query (connection)　　
cross-connect (less used):select * from a a B
Inner Connection ( Natural connection ):SELECT * from a INNER join B on a. field = B. field;
implicit inner joins:select * from A, A where A. field = B. field;
External Connection
left outer connection:SELECT * from a ieft outer join B on A. field = B. field;
right outer connection:SELECT * from a-outer join B on a. field = B. field;
hql Multi-table Query　　
cross-Connect, inner connection, implicit inner connection, urgent inner connection, left outer connection, urgent left outer connection, right outer connection
Implicit in-connection (learn)
createquery ("from Order o where o.customer.name like ' t% '");
equivalent to: from Order o join O.customer C where c.name like ' t% '
HQL and urgent inner connection differences (other similar):
INNER JOIN query: Encapsulates the data in a list<object[]>.
Urgent Internal connection: encapsulates the data in a list<customer>. But the urgency of the connection, get a duplicate record, you need to use distinct weight.

//Internal connection query:Query query = Session.createquery ("from Customer C inner join C.orders"); List<Object[]> list =query.list (); for(object[] objects:list) {Customer C= (Customer) objects[0]; Order o= (Order) objects[1]; System.out.println (C.getcid ()+ "" "+c.getcname () +" "+c.getage ()); System.out.println (o.getoid ()+" "+o.getaddr ());}//Urgent Internal connection: Using a keyword fetch (HQL)Query query = session.createquery ("SELECT DISTINCT C from Customer C INNER join fetch c.orders"); List<Customer> list =query.list (); for(Customer customer:list) {System.out.println (customer);}

QBC
　　1. Querying All Records

list<customer> list = Session.createcriteria (Customer.  Class). List ();  for (Customer customer:list) {System.out.println (customer);}

　　2. Sorting

list<customer> list = Session.createcriteria (Customer.  Class). AddOrder (Org.hibernate.criterion.Order.desc ("id")). List ();  for (Customer customer:list) {System.out.println (customer);}

　　3. Paging

Criteria = Session.createcriteria (Order.  Class); Criteria.setfirstresult ();criteria.setmaxresults (ten); List<Order> list = criteria.list ();  for (Order order:list) {System.out.println (order);}

　　4. Get a single object

Customer customer = (customer) Session.createcriteria (customer).  Class). Add (Restrictions.eq ("CNAME", "xiaoming")). Uniqueresult (); SYSTEM.OUT.PRINTLN (customer);

　　5. Queries with parameters

list<customer> list = Session.createcriteria (Customer.  Class). Add (Restrictions.eq ("CNAME", "xiaoming")). List (); SYSTEM.OUT.PRINTLN (list); List<Customer> list = Session.createcriteria (Customer.  Class). Add (Restrictions.eq ("CNAME", "xiaoming")). Add (Restrictions.eq ("CID", 2)). List (); SYSTEM.OUT.PRINTLN (list);

　　6. Fuzzy query

Criteria = Session.createcriteria (Customer.  Class); Criteria.add (Restrictions.like ("CNAME", "large%")); List<Customer> list = criteria.list (); SYSTEM.OUT.PRINTLN (list);

Sql

list<object[]> list = Session.createsqlquery ("SELECT * from Customer"). List ();  for (object[] objects:list) {System.out.println (Arrays.tostring (objects));} List<Customer> list = Session.createsqlquery ("SELECT * from Customer"). Addentity (Customer. class ). List ();  for (Customer customer:list) {System.out.println (customer);}

Offline query
　　

@Test/** Offline conditional query*/ Public voidDemo () {//encapsulation of the Web tierDetachedcriteria criteria = Detachedcriteria.forclass (Customer.class); Criteria.add (Restrictions.eq ("CNAME", "xiaoming")); Criteria.add (Restrictions.eq ("CID", 2)); //pass to the DAO layerSession session =hibernateutils.opensession (); Transaction TX=session.begintransaction (); Criteria C1=Criteria.getexecutablecriteria (session); List<Customer> list =c1.list ();　　SYSTEM.OUT.PRINTLN (list);　　Tx.commit (); Session.close ();}

How hibernate is retrieved