查询条件为空的话就不要传在sql里面了
SELECT * FROM 订单 where 1=1 ${if(len(area) == 0,""," and 货主地区 = '" + area + "'")}
下拉框参数为空选择全部-http://help.finereport.com/doc-view-2394.html#5
${if(bm='',""," and 所属部门 in('"+bm+"')")}
where 1=1
${if(isnull(参数名),""," and 对应字段='"+参数名+"'")}