为什么用.Merge合并查询不成功
一张表只有 car_fee_flag = 1和car_fee_flag = 2两个查询条件不同。现在用.Merge合并两个查询条件，但是现在只能返回一个查询结果。我想要把两个查询结果并列的显示在一个表中(一、二列)

C# code

private void b_lookfor_Click(object sender, EventArgs e)        {            string sql_str = "";            DataTable dt1 = new DataTable();            DataTable dt2 = new DataTable();            fee_conn fee_conn = new fee_conn();            SqlDataAdapter find_do;            if (DateTime.Compare(d_end, d_start) > 0)            {                                SqlConnection conn = new SqlConnection(fee_conn.sql_conn());                sql_str = "select * from car_park_fee where car_fee_flag = 1";                find_do = new SqlDataAdapter(sql_str, conn);                find_do.Fill(dt1);                sql_str = "select * from car_park_fee where car_fee_flag = 2";                find_do = new SqlDataAdapter(sql_str, conn);                find_do.Fill(dt2);                dt1.Merge(dt2);                d_report.Visible = true;                d_report.DataSource = dt1;                                                }       }