<select id="findUserByIds" parameterType="com.pojo.QueryVo" resultType="com.pojo.User">

        SELECT * from USER

      <where>

          <if test="ids !=null">

              <!--

              foreach:循环传入的集合参数

              collection:传入的集合的变量名称

              item:每次循环将循环出的数据放入这个变量中

              open循环开始拼接的字符串

              separator:循环中拼接的分隔符

              -->

              <foreach collection="ids" item="id" open="id in(" close=")" separator=",">

              #{id}

              </foreach>

          </if>

      </where>

    </select>