Rails Error :Column 'id' in order clause is ambiguous

错误Column 'id' in order clause is ambiguous 易出现在

p  =  Product.find(:all,:include => :kind,:order => " id desc " )

类似的语句上,用include包含了一个left join对象,所以id可能存在于多个表内,就引起了二义性
修改为

p  =  Product.find(:all,:include => :kind,:order => " products.id desc " )

属性前加上表名
一切OK