使用mybatis一对多:
使用collection 标签:
collection属性:
property: 指的是集合属性的值.
ofType：指的是集合中元素的类型.
<collection property="products" ofType="com.xx.xxx"></collection>
例:在resultMap标签中
<collection property="teachers" ofType="com.xxx.xxxx.products">
<id property="tid" column="id"/>
<result property="tname" column="tname"/>
</collection>
注意:查询的时候如果关联表字段重复需要重命名.
例如:<id property="tid" column="id"/>
<resultMap id="userMap" type="com.xxx.xxx.User">
<id property="id" column="id"/>
<result property="username" column="username"/>
<result property="birthday" column="birthday"/>
<result property="sex" column="sex"/>
<result property="address" column="address"/>
<collection property="roles" ofType="com.example.domain.Role" resultMap="roleMap"/>
</resultMap>
<resultMap id="roleMap" type="com.xxx.xxx.Role">
<id property="roleId" column="rid"/>
<result property="roleName" column="ROLE_NAME"/>
<result property="roleDesc" column="ROLE_DESC"/>
</resultMap>
<select id="findAll" resultMap="userMap">
SELECT u.*,r.ID as rid,r.ROLE_DESC,r.ROLE_NAME FROM user u
LEFT OUTER JOIN user_role ur on u.id = ur.UID
LEFT OUTER JOIN role r on ur.RID = r.ID
</select>
使用mybatis一对一
使用association标签
property: 指的是集合属性的值.
javaType:指定关联的类型
<association property="People" javaType="com.xxx.xxx.user">
:
