Tom27(提问者)select a.产品ID,a.产品名称,b.类别ID,b.类别名称, c.数量 from 产品 a
left join 产品类别 b on a.类别ID = b.类别ID
left join 订单明细 c on a.产品ID = c.产品ID
where 1=1
${if(len(category)=0,'',"and a.类别ID in ('"+category+"')")}
${if(len(product)=0,'',"and a.产品ID in ('"+product+"')")}