What are the query methods of Hibernate in HQL
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1. Support parameter passing query in string mode:
Example:
List students = session.createQuery ("select s.iddres.name from Student s where s.name like'% 1'"). List (); for (Iterator iter=students.iterator (); iter.hasNext ();) {Object [] o = (Object []) iter.next (); System.out.println (o [0] + "," + o [1]);}
Because multiple attribute queries are involved, the Object array type is returned.
2. Support something similar to PrepareStatement? Pass parameter query
Example:
List students = session.createQuery ("select s.iddres.name from Student s where s.name like: goodname") .setParameter ("goodname", "% 1%") .list (); for (Iterator iter=students.iterator (); iter.hasNext ();) {Object [] o = (Object []) iter.next () System.out.println (o [0] + "," + o [1]);}
To set the parameter from 0, see line 2.
3. Parameter transfer in de-variable mode
Example:
List students = session.createQuery ("select s.iddres.name from Student s where s.name like: goodname") .setParameter ("goodname", "% 1%") .list (); for (Iterator iter=students.iterator (); iter.hasNext ();) {Object [] o = (Object []) iter.next () System.out.println (o [0] + "," + o [1]);}
This is similar to the one in 2, except that the extra parameters can be grouped into one category.
4. Support multi-parameter transmission
Example:
List students = session.createQuery ("select s.id, s.name from Student s where s.id in (: myids)") .setParameterList ("myids", new Object [] {1,2,3,4,5 Iterator iter=students.iterator (); iter.hasNext ();) {Object [] o = (Object []) iter.next () System.out.println (o [0] + "," + o [1]);}
Notice that the calling method is setParameterList.
5. Call the functions in the database
Example:
List students = session.createQuery ("select s.id, s.name from Student s where date_format (s.createTime,'% YMY% m') =?") .setParameter (0, "2008-10") .list (); for (Iterator iter=students.iterator (); iter.hasNext ();) {Object [] o = (Object []) iter.next () System.out.println (o [0] + "," + o [1]);}
Database function date_format.
6. Directly support sql query
Example:
List students = session.createSQLQuery ("select * from t_student"). List (); for (Iterator iter=students.iterator (); iter.hasNext ();) {Object [] o = (Object []) iter.next (); System.out.println (o [0] + "," + o [1]);}
You just need to call the createSQLQuery method in session.
7. Make navigation query
Example:
List students = session.createQuery ("select s.name from Student s where s.classes.name like'% 1%'"). List (); for (Iterator iter=students.iterator (); iter.hasNext ();) {String s = (String) iter.next (); System.out.println (s);}
This kind of inquiry is very convenient.
8. Paging query
Example:
List students = session.createQuery ("from Student"). SetFirstResult (0) .setMaxResults (3). List (); for (Iterator iter=students.iterator (); iter.hasNext ();) {Student student = (Student) iter.next (); System.out.println (student.getName ());}
This is a very simple paging query, the implementation of paging query is much more complex, paging query is equivalent to the limit in the database, to limit the number of entries displayed in a query.
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