请教下 怎么在数据集参数里面使用多重if语句,问帆软客户他就告诉我直接拼接,我TM知道怎么拼接还问?源代码:${if(len(ystr)==0 && len(yend)==0,""," AND MFG.YSBITM_0 IN (SELECT ITMREF_0 FROM YOPPPJM WHERE 1=1${if(len('"+ystr+"')==0,""," AND to_char(YJQ_0,'YYYY/MM/dd')>='"+ystr+"'")} ${if(len('"+yend+"')==0,""," AND to_char(YJQ_0,'YYYY/MM/dd')<='"+yend+"'")} )")}