select strftime('%Y-%m',d.订购日期) as 订购年月,count(d.订单ID) as 订单数量,sum(dm.单价*dm.数量*(1-dm.折扣)) as 月销售,strftime('%Y',订购日期) as 年,strftime('%m',订购日期) as 月 FROM 订单 d join 订单明细 dm on d.订单ID=dm.订单ID where 年=('${year}') and 月 in ('${mid}') and 是否已付=('${tf}') group by strftime('%Y-%m',订购日期) order by 年;怎么把where后边的多个参数变成这种形式${if(len(year) == 0,"","and 年 in ('" + year + "')")}