dao

List<TProject> queryProjectByCondition(ProjectParamByCondition projectParamByCondition);

xml文件

    <select id="queryProjectByCondition" resultType="cn.cdqf.mydmsjportal.pojo.TProject">
        select *
        from t_project where 1=1

        <if test="typeId!=-1">
          and typeId=#{typeId}
        </if>
        <if test="status!=-1">
          and status=#{status}
        </if>
        <if test="projectName!='' and projectName!=null ">
          and projectName like concat('%',#{projectName},'%')
        </if>

        <if test="orderBy!='-1'">
          ORDER BY #{orderBy} DESC
        </if>
    </select>

原因与解决

ORDER BY #{orderBy} DESC会被解析成ORDER BY “orderBy” DESC，也就是会加上引号，这是为了解决sql注入，如果要不加引号，可以使用$符号，ORDER BY ${orderBy} DESC就可以了。