Mybatis提供了很好的支持來處理一對多查詢問題。下面是一些處理一對多查詢問題的方法：

1. 使用嵌套查詢：在主查詢中進行嵌套查詢，通過主查詢的結果來獲取關聯的多個子對象。例如，可以使用<collection>標簽來定義一對多的關聯關系。

<resultMap id="userMap" type="User">
  <id column="id" property="id" />
  <result column="name" property="name" />
  <collection property="orders" ofType="Order">
    <id column="order_id" property="id" />
    <result column="order_name" property="name" />
  </collection>
</resultMap>

<select id="getUserWithOrders" resultMap="userMap">
  SELECT u.id, u.name, o.id as order_id, o.name as order_name
  FROM user u
  LEFT JOIN order o ON u.id = o.user_id
  WHERE u.id = #{id}
</select>

2. 使用嵌套查詢映射：如果一對多的關系比較復雜，可以考慮使用嵌套查詢映射來處理。通過在主查詢中使用<association>標簽來定義關聯對象，然后在關聯對象的映射中使用<collection>標簽來定義關聯的多個子對象。

<resultMap id="userMap" type="User">
  <id column="id" property="id" />
  <result column="name" property="name" />
  <association property="department" javaType="Department">
    <id column="department_id" property="id" />
    <result column="department_name" property="name" />
    <collection property="employees" ofType="Employee">
      <id column="employee_id" property="id" />
      <result column="employee_name" property="name" />
    </collection>
  </association>
</resultMap>

<select id="getUserWithDepartmentAndEmployees" resultMap="userMap">
  SELECT u.id, u.name, d.id as department_id, d.name as department_name, e.id as employee_id, e.name as employee_name
  FROM user u
  LEFT JOIN department d ON u.department_id = d.id
  LEFT JOIN employee e ON d.id = e.department_id
  WHERE u.id = #{id}
</select>

3. 使用嵌套查詢的方式來處理：在查詢主對象的同時，通過子查詢來獲取關聯的多個子對象。這種方式適用于一對多關系比較簡單的情況。

<select id="getUserWithOrders" resultType="User">
  SELECT u.id, u.name, (SELECT o.id, o.name FROM order o WHERE o.user_id = u.id) as orders
  FROM user u
  WHERE u.id = #{id}
</select>

這些方法可以根據具體的業務需求來選擇使用，可以根據關聯關系的復雜程度和查詢性能來進行選擇。