# 16.4\. 定制装载SQL 你可能需要声明你自己的SQL(或HQL)来装载实体 ``` <sql-query name="person"> <return alias="pers" class="Person" lock-mode="upgrade"/> SELECT NAME AS {pers.name}, ID AS {pers.id} FROM PERSON WHERE ID=? FOR UPDATE </sql-query> ``` 这只是一个前面讨论过的命名查询声明，你可以在类映射里引用这个命名查询。 ``` <class name="Person"> <id name="id"> <generator class="increment"/> </id> <property name="name" not-null="true"/> <loader query-ref="person"/> </class> ``` 这也可以用于存储过程 你甚至可以定一个用于集合装载的查询: ``` <set name="employments" inverse="true"> <key/> <one-to-many class="Employment"/> <loader query-ref="employments"/> </set> ``` ``` <sql-query name="employments"> <load-collection alias="emp" role="Person.employments"/> SELECT {emp.*} FROM EMPLOYMENT emp WHERE EMPLOYER = :id ORDER BY STARTDATE ASC, EMPLOYEE ASC </sql-query> ``` 你甚至还可以定义一个实体装载器，它通过连接抓取装载一个集合: ``` <sql-query name="person"> <return alias="pers" class="Person"/> <return-join alias="emp" property="pers.employments"/> SELECT NAME AS {pers.*}, {emp.*} FROM PERSON pers LEFT OUTER JOIN EMPLOYMENT emp ON pers.ID = emp.PERSON_ID WHERE ID=? </sql-query> ```