查询多列数据时用这种方法查询

 1  private void cbbType_SelectedIndexChanged(object sender, EventArgs e)
 2         {
 3             //清空DN列
 4             cbbDn.Items.Clear();
 5             //字段清除
 6             FieldListSaddle.Clear();
 7             //加入字段
 8             FieldListSaddle.Add("Baojiao,Drawing,Table,Ribs,Type1,HasPad");
 9             //定义查询条件
10             string where = string.Format("DnX < {0} and DnD >= {0} and Type2 = ‘{1}‘", DI, cbbType.Text);
11             //按照条件查询表
12             tbBiao = GetAccessData(TypeName, FieldListSaddle, where);
13             //如果表中有两列数据则需要循环查找并添加
14             for (int i = 0; i < tbBiao.Rows.Count; i++)
15             {
16                 //表名等于第一行数据的表
17                 string TableName = (tbBiao.Rows[i]["Table"]).ToString();
18                 //查询出DN表放入内存
19                 tbDn = GetAccessData(TableName);
20                 //查询出符合DN的那一列
21                 DnList = tbDn.AsEnumerable().Select(p => p.Field<double>("DN").ToString()).Distinct().ToList();
22                 //加入控件中
23                 cbbDn.Items.AddRange(DnList.ToArray());
24             }
25         }