<where>  
<if test="propertyid!=null and propertyid!= '' ">
    propertyid = ${propertyid}
</if>
</where>

-- 如果想使用in的方式，需要在请求参数里把propertyid设置为list类型
<where>  
    <if test='propertyid != null'>
    propertyid in  
    <foreach collection="propertyid" open="(" close=")" separator="," item="propertyid">
        ${propertyid}
    </foreach>
    </if>
</where>