怎样用hibernate的hql查询查询成map或list

这里制作一个引子，具体内容比较多，而且hibernate文档里的hql篇写的很详细

可以这么用：

List list = getHibernateTemplate().find("select new map(t1.c1,t2.c3) from table1 t1 ,table2 t2 where t1.c1=t2.c2");

这样的话list里的每个元素都是一个map，每个map里包含两个元素

注意：这里的table1和table2都是class名并不是真的表名，毕竟这是hql。除了可以用map还还支持list和自定义的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";

由于from之前的空格，引起unexpected token: 　from

//select new

给一个构建函数：

public class Department(Department d, Integer employeeSize)

然后写成这样：

SELECT new Department(department, count(employee.id)) FROM .....

Java代码


//查询其中几个字段,添加new map(),注意map里的m是小写的。也不需要导入包，这样通过query.list()出来的list里存放的不再是默认的Object数组了，而是map集合了

120. String hql = " select new map(name,passwd) from Users";

121. Query query = session.createQuery(hql);

122. //默认查询出来的list里存放的是一个Object数组，但是在这里list里存放的不再是默认的Object数组了，而是Map集合了

123. List<Map> list = query.list();

124. for(Map user : list){

125. //一条记录里所有的字段值都是map里的一个元素,key是字符串0,1,2,3....，value是字段值

126. //如果将hql改为：String hql = " select new map(name as username,passwd as password) from Users";,那么key将不是字符串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. 输出结果为：

134. name1 : password1

135. name2 : password2

136. name3 : password3

137. */

138.//查询其中几个字段,添加new map(),注意map里的m是小写的。也不需要导入包，这样通过query.list()出来的list里存放的不再是默认的Object数组了，而是map集合了

139. String hql = " select new map(name,passwd) from Users";

140. Query query = session.createQuery(hql);

141. //默认查询出来的list里存放的是一个Object数组，但是在这里list里存放的不再是默认的Object数组了，而是Map集合了

142. List<Map> list = query.list();

143. for(Map user : list){

144. //一条记录里所有的字段值都是map里的一个元素,key是字符串0,1,2,3....，value是字段值

145. //如果将hql改为：String hql = " select new map(name as username,passwd as password) from Users";,那么key将不是字符串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. 输出结果为：

153. name1 : password1

154. name2 : password2

155. name3 : password3

156. */