web页面查询数据库，GridView不显示数据
我在web页面添加了一个GridView,在页面load里面写了查询语句。但在运行后在页面上没有数据，也看不到GridView。数据库里是有相应数据的，是不是sql查询语句有错？

C# code

using System;using System.Collections;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Xml.Linq;using System.Data.SqlClient;public partial class 子页面_1 : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {        DateTime currentTime,a,b;//a和b为起止时间        currentTime = System.DateTime.Now;        if (System.DateTime.Now.Hour >= 20)        {            a = currentTime.Date.AddHours(-3);            b = a.AddHours(23);        }        else        {            a = currentTime.Date.AddHours(-27);            b = currentTime.Date.AddHours(-4);        }         //查询时段a-b的数据        string ConStr = "server=IBM;user id=sa;pwd=sa;database=dataserver";        SqlConnection con = new SqlConnection(ConStr);        string SqlStr = "select * from tb_hourdata where 时次>='" + a + "' and 时次<='" + b + "'order by 站号 ASC";        con.Open();        SqlDataAdapter da = new SqlDataAdapter(SqlStr, con);        DataSet ds = new DataSet();        da.Fill(ds);        GridView1.DataSource = ds;        GridView1.DataBind();        con.Close();    }}

[解决办法]
你把
select * from tb_hourdata where 时次>='" + a + "' and 时次<='" + b + "'order by 站号 ASC
调试 出来，放到sql server查询下是否有数据
[解决办法]
设个断点看看就知道了