Hibernate查詢_HQL_EJBQL_QBC_QBE
阿新 • • 發佈：2018-11-17
detach and 自己 code 數據表 面向 dde obj ejb 
@Test
2
public void testHQL_34() {
3
Session session = sf.openSession();
4 session.beginTransaction();
5 //下面查詢使用的函數是Session的createSQLQuery
6 SQLQuery q = session.createSQLQuery("select * from category limit 2,4").addEntity(Category.class);
7
8
for(Category c : categories) {
9 System.out.println(c.getName());
10
}
11 session.getTransaction().commit();
12 session.close();
13
14
}
@Test
2 public void testHQL_02() {
3
4 session.beginTransaction();
5 //Category是對象名而不是數據表名
6 Query q = session.createQuery("from Category c where c.name > ‘c5‘");
7 List<Category> categories = (List<Category>)q.list();
8 for(Category c : categories) {
9
10 }
11 session.getTransaction().commit();
12 session.close();
13
14 }
@Test
2 public void testQBC() {
3 Session session = sf.openSession();
4 session.beginTransaction();
5 //criterion 標準/準則/約束
6 Criteria c = session.createCriteria(Topic.class) //from Topic
7
8 .add(Restrictions.gt("id", 2)) //greater than = id > 2
9 .add(Restrictions.lt("id", 8)) //little than = id < 8
10 .add(Restrictions.like("title", "t_"))
11 .createCriteria("category")
12 .add(Restrictions.between("id", 3, 5)) //category.id >= 3 and category.id <=5
13 ;
14
15 //DetachedCriterea
16 for(Object o : c.list()) {
17 Topic t = (Topic)o;
18 System.out.println(t.getId() + "-" + t.getTitle());
19 }
20 session.getTransaction().commit();
21 session.close();
22
23 }
@Test
2 public void testQBE() {
3 Session session = sf.openSession();
4 session.beginTransaction();
5 Topic tExample = new Topic();
6 tExample.setTitle("T_");
7
8 //創建一個例子對象，然後設置其相應的屬性
9 //QBE僅適合於給特定值的查詢
10 Example e = Example.create(tExample)
11 .ignoreCase().enableLike();
12 //QBC除了添加自己的條件，最後將例子對象e也當成條件添加進來
13 //QBC可以添加給特定值的條件，也可添加給了一定範圍的條件
14 Criteria c = session.createCriteria(Topic.class)
15 .add(Restrictions.gt("id", 2))
16 .add(Restrictions.lt("id", 8))
17 .add(e)
18 ;
19 //from Topic t where t.id>2 and t.id<8 and t.title like ‘T_‘
20
21
22 for(Object o : c.list()) {
23 Topic t = (Topic)o;
24 System.out.println(t.getId() + "-" + t.getTitle());
25 }
26 session.getTransaction().commit();
27 session.close();
28
29 }
查詢按功能強弱可以分為以下幾種：
Native SQL > HQL > EJBQL > QBC > QBE
1、Native SQL
Native SQL為數據庫系統本身的SQL，裏面包含了一些特有的函數等，功能也最為強大。
如：
@Test2
public void testHQL_34() {3
Session session = sf.openSession();4
session.beginTransaction();5
//下面查詢使用的函數是Session的createSQLQuery6
SQLQuery q = session.createSQLQuery("select * from category limit 2,4").addEntity(Category.class);7
8
for(Category c : categories) {9
System.out.println(c.getName());10
}11
session.getTransaction().commit();12
session.close();13
14
}
2、HQL
Hibernate提供的面向對象查詢語言。
如：
@Test2
public void testHQL_02() {3
4
session.beginTransaction();5
//Category是對象名而不是數據表名6
Query q = session.createQuery("from Category c where c.name > ‘c5‘");7
List<Category> categories = (List<Category>)q.list();8
for(Category c : categories) {9
10
}11
session.getTransaction().commit();12
session.close();13
14
}
3、EJBQL
與HQL類似，是HQL的一個子集
4、QBC
Query By Criteria，即帶約束/條件的查詢
如：
@Test2
public void testQBC() {3
Session session = sf.openSession();4
session.beginTransaction();5
//criterion 標準/準則/約束6
Criteria c = session.createCriteria(Topic.class) //from Topic7
8
.add(Restrictions.gt("id", 2)) //greater than = id > 29
.add(Restrictions.lt("id", 8)) //little than = id < 810
.add(Restrictions.like("title", "t_"))11
.createCriteria("category")12
.add(Restrictions.between("id", 3, 5)) //category.id >= 3 and category.id <=513
;14
15
//DetachedCriterea16
for(Object o : c.list()) {17
Topic t = (Topic)o;18
System.out.println(t.getId() + "-" + t.getTitle());19
}20
session.getTransaction().commit();21
session.close();22
23
}
5、QBE
Query By Example
如：
@Test2
public void testQBE() {3
Session session = sf.openSession();4
session.beginTransaction();5
Topic tExample = new Topic();6
tExample.setTitle("T_");7
8
//創建一個例子對象，然後設置其相應的屬性9
//QBE僅適合於給特定值的查詢10
Example e = Example.create(tExample)11
.ignoreCase().enableLike();12
//QBC除了添加自己的條件，最後將例子對象e也當成條件添加進來13
//QBC可以添加給特定值的條件，也可添加給了一定範圍的條件14
Criteria c = session.createCriteria(Topic.class)15
.add(Restrictions.gt("id", 2))16
.add(Restrictions.lt("id", 8))17
.add(e)18
;19
//from Topic t where t.id>2 and t.id<8 and t.title like ‘T_‘20
21
22
for(Object o : c.list()) {23
Topic t = (Topic)o;24
System.out.println(t.getId() + "-" + t.getTitle());25
}26
session.getTransaction().commit();27
session.close();28
29
}
以上幾種方法，其中QBC、QBE更加符合面向對象編程（僅此而已）。
Hibernate查詢_HQL_EJBQL_QBC_QBE