MyBatis SQL分页处理及查询总数据量

查询数据总数：
<select id="selectCount" resultType="java.lang.Integer">
    <!--
      WARNING - @mbggenerated
      This element is automatically generated by MyBatis Generator, do not modify.
    -->
    select
        count(id)
    from
        tb_user
    <where >
      <if test="username != null" >
       and username like '%${username,jdbcType=VARCHAR}%'
      </if>
      <if test="start_time != null" >
        and addtime &gt;= #{start_time,jdbcType=TIMESTAMP}
      </if>
      <if test="end_time != null" >
        and addtime &lt;= #{end_time,jdbcType=TIMESTAMP}
      </if>
    </where>
  </select>

分页查询：
  <select id="getUserForPage" resultMap="BaseResultMap"  >
    <!--
      WARNING - @mbggenerated
      This element is automatically generated by MyBatis Generator, do not modify.
    -->
    select
        <include refid="Base_Column_List" />
    from
        tb_user
    <where >
      <if test="username != null" >
       and username like '%${username,jdbcType=VARCHAR}%'
      </if>
      <if test="start_time != null" >
        and addtime &gt;= #{start_time,jdbcType=TIMESTAMP}
      </if>
      <if test="end_time != null" >
        and addtime &lt;= #{end_time,jdbcType=TIMESTAMP}
      </if>
    </where>
    limit #{index},#{num}
  </select>