在where语句中使用以下两个and条件可以查询出相应结果。and u.no='37040305'and un.varsec_id ='2019090606' 但使用以下参数,并将默认值设为以上数值时,查询结果应同上面的条件,但为什么查询为空呢?难道参数格式或语句有问题,麻烦给检查指正,谢谢。${if(len(kh)=0," "," and u.no= ' "+kh+" ' ")} ${if(len(wzzl)=0," "," and un.varsec_id= ' "+wzzl+" ' ")}