mybatis动态排序

   <select id="getLinkTypeListByCondition" parameterType="java.util.Map"  resultMap="linkType">
        SELECT * FROM OD_LINK_TYPE
        <where>
            LINK_URI != BASE_TYPE_URI
            <if test="linkUri != null">
               AND LINK_URI LIKE '%${linkUri}%'
            if>
            <if test="linkLabel != null">
                AND LINK_LABEL LIKE '%${linkLabel}%'
            if>
            <if test="baseTypeUri != null">
                AND BASE_TYPE_URI=#{baseTypeUri}
            if>
        where>
      <if test="orderfield != null" >
         ORDER BY 
           <choose>    
                <when test="orderfield == 'linkUri'">    
                    LINK_URI ${orderdir} 
                when>  
                 <when test="orderfield == 'linkLabel'">    
                    LINK_LABEL ${orderdir} 
                when>  
                 <otherwise>
                   BASE_TYPE_URI ${orderdir}
                otherwise> 
            choose>    
        if>
    select>