怎樣用hibernate的hql查詢查詢成map或list

博客分類：

• hibernate

HibernateBean

這裏製作一個引子，具體內容比較多，而且hibernate文檔裏的hql篇寫的很詳細
可以這麼用：
List list = getHibernateTemplate().find("select new map(t1.c1,t2.c3) from table1 t1 ,table2 t2 where t1.c1=t2.c2");
這樣的話list裏的每個元素都是一個map，每個map裏包含兩個元素
注意：這裏的table1和table2都是class名並不是真的表名，畢竟這是hql。除了可以用map還還支持list和自定義的bean。

//HQL-Associations
String hql = "select s.name, p.name, p.price from Product p inner join p.supplier as s";
Query query = session.createQuery(hql);
List results = query.list();

//HQL-Delete
String hql = "delete from Product where name = :name";
Query query = session.createQuery(hql);
query.setString("name","Product 1");
int rowCount = query.executeUpdate();

//HQL-Function
String hql = "select min(product.price), max(product.price) from Product product";
Query query = session.createQuery(hql);
List results = query.list();

//HQL-Fetch Associations HQL Inner Join
String hql = "from Supplier s inner join fetch s.products as p";
Query query = session.createQuery(hql);
List results = query.list();

//HQL-Named Parameters
String hql = "from Product where price > :price";
Query query = session.createQuery(hql);
query.setDouble("price",2.0);
List results = query.list();
String hql = "from Product as product where product.supplier=:supplier";
Query query = session.createQuery(hql);
query.setEntity("supplier",supplier);
List results = query.list();

//HQL-Update
String hql = "update Supplier set name = :newName where name = :name";
Query query = session.createQuery(hql);
query.setString("name","Supplier Name 1");
query.setString("newName","s1");
int rowCount = query.executeUpdate();

//HQL-where
String hql = "from Product where price > 2.0 and name like 'P%'";
Query query = session.createQuery(hql);
List results = query.list();

//HQL-Map
String hql = " select new map(usr.name as userName, usr.password as password) from User usr";
Query query = session.createQuery(hql);
List list = query.list();
Map goods =(Map)list.get(0);

【注】
   String hql = " select new map(usr.name as userName, usr.password as password)　from com.jason.User usr";
   String hql = " select new map(usr.name as userName, usr.password as password) from com.jason.User usr";
由於from之前的空格，引起unexpected token: 　from



//select new

給一個構建函數：
public class Department(Department d, Integer employeeSize)

然後寫成這樣：
SELECT new Department(department, count(employee.id)) FROM .....

//查詢其中幾個字段,添加new map(),注意map裏的m是小寫的。也不需要導入包，這樣通過query.list()出來的list裏存放的不再是默認的Object數組了，而是map集合了
120. String hql = " select new map(name,passwd) from Users";
121. Query query = session.createQuery(hql);
122. //默認查詢出來的list裏存放的是一個Object數組，但是在這裏list裏存放的不再是默認的Object數組了，而是Map集合了
123. List<Map> list = query.list();
124. for(Map user : list){
125. //一條記錄裏所有的字段值都是map裏的一個元素,key是字符串0,1,2,3....，value是字段值
126. //如果將hql改爲：String hql = " select new map(name as username,passwd as password) from Users";,那麼key將不是字符串0,1,2...了，而是"username","password"了
127. String name = (String)user.get("0");//get("0");是get(key),注意:0,1,2...是字符串，而不是整形
128. String passwd = (String)user.get("1");
129.
130. System.out.println(name + " : " + passwd);
131. }
132. /**
133. 輸出結果爲：
134. name1 : password1
135. name2 : password2
136. name3 : password3
137. */
138.//查詢其中幾個字段,添加new map(),注意map裏的m是小寫的。也不需要導入包，這樣通過query.list()出來的list裏存放的不再是默認的Object數組了，而是map集合了
139. String hql = " select new map(name,passwd) from Users";
140. Query query = session.createQuery(hql);
141. //默認查詢出來的list裏存放的是一個Object數組，但是在這裏list裏存放的不再是默認的Object數組了，而是Map集合了
142. List<Map> list = query.list();
143. for(Map user : list){
144. //一條記錄裏所有的字段值都是map裏的一個元素,key是字符串0,1,2,3....，value是字段值
145. //如果將hql改爲：String hql = " select new map(name as username,passwd as password) from Users";,那麼key將不是字符串0,1,2...了，而是"username","password"了
146. String name = (String)user.get("0");//get("0");是get(key),注意:0,1,2...是字符串，而不是整形
147. String passwd = (String)user.get("1");
148.
149. System.out.println(name + " : " + passwd);
150. }
151. /**
152. 輸出結果爲：
153. name1 : password1
154. name2 : password2
155. name3 : password3
156. */