DataTable dt1 = null, dt2 = null, dt3 = null, dt4 = null;
            foreach(var item in dt1.Select("XX=XX"))
            {
                dt3.Rows.Add(item);
            }

            foreach(var item in dt1.Select("XX=XX2"))
            {
                dt4.Rows.Add(item);
            }

            foreach (var item in dt2.Select("XX=XX"))
            {
                dt3.Rows.Add(item);
            }

            foreach (var item in dt2.Select("XX=XX2"))
            {
                dt4.Rows.Add(item);
            }
            grid1.DataSource = dt3;
            grid2.DataSource = dt4;

------解决方案--------------------

首先按照“where 类别=1 or 类别=2”来查询，然后再内存中再分为两个集合，分别绑定到两个GridView。