使用存储过程asp.net进行动态搜索

在asp.net中使用存储过程实现动态搜索时遇到问题我有一个考勤系统的数据表和数据库，我想搜索一个有主要控件的员工，比如他的ID和日期，设备类型。。。等这是我的Default.aspx代码

public partial class _Default : Page
{
    static string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;

    protected void Page_Load(object sender, EventArgs e)
    {
        if (IsPostBack == false)
        {
            this.gridData();
            this.search();
        }
    }
    //--------------------------------------------------
    private void gridData()
    {
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand("SELECT EventUserId, EventDate, EventTime, Eventtype, Readerid FROM V_EventLogs"))
            {
                using (SqlDataAdapter sda = new SqlDataAdapter())
                {
                    DataTable dt = new DataTable();
                    cmd.Connection = con;
                    sda.SelectCommand = cmd;
                    sda.Fill(dt);
                    GridView1.DataSource = dt;
                    GridView1.DataBind();
                }
            }
        }
    }
    private DataTable search()
    {
        DataTable sdt = new DataTable();
        SqlConnection con = new SqlConnection(constr);
        try
        {
            SqlCommand cmd = new SqlCommand("userSearch", con);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.CommandTimeout = 300;
            cmd.Parameters.AddWithValue("@EventUserId", TextBox1.Text);
            cmd.Parameters.AddWithValue("@EventDateFrm", ASPxDateEdit1.Text);
            cmd.Parameters.AddWithValue("@EventDateTo", ASPxDateEdit2.Text);
            cmd.Parameters.AddWithValue("@Readerid", txtReader.Text);
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
            // passs parameter to data adapter
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            sda.Fill(sdt);
        }
        catch (Exception ex)            {
            Response.Write(ex);
        }
        return sdt;
    }

   //---------------------------------------------------

    protected void OnPageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        GridView1.PageIndex = e.NewPageIndex;
        this.gridData();
    }
    protected void btnSearch_Click(object sender, EventArgs e)
    {    
        GridView1.DataSource = search();
        GridView1.DataBind();
    }
}

}

这是我的Default.aspx页面：

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication1._Default" %>

<div class="jumbotron">
    <h1>BioWeb TimeTel</h1>
    <p class="lead">Time Attendance</p>
    <%--<p><a href="http://www.asp.net" class="btn btn-primary btn-lg">Learn more &raquo;</a></p>--%>
</div>
<div>
        User ID:
        &nbsp;<asp:TextBox ID="TextBox1" runat="server" CssClass="form-control"></asp:TextBox>
        &nbsp;
        <br />
        <br />
        Event Date:
        &nbsp;&nbsp;
        <br />
        <dx:ASPxDateEdit ID="ASPxDateEdit1" runat="server" DisplayFormatString="MM/dd/yyyy" EditFormatString="MM/dd/yyyy">
        </dx:ASPxDateEdit>
        <br />
        Event Time:
        <br />
        &nbsp;<dx:ASPxDateEdit ID="ASPxDateEdit2" runat="server" DisplayFormatString="MM/dd/yyyy" EditFormatString="MM/dd/yyyy">
        </dx:ASPxDateEdit>
        &nbsp;
        <br />
        <br />
        Reader:
        &nbsp;<asp:TextBox ID="txtReader" runat="server" CssClass="form-control" AutoCompleteType="Disabled"></asp:TextBox>
        &nbsp;
        <br />
        <br />
        &nbsp
        <br />
        <br />
        <asp:Button ID="btnSearch" runat="server" Text="Search" OnClick="btnSearch_Click" CssClass="btn btn-primary btn-lg" OnLoad="Page_Load" />
        <br />
        <br />
        <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" AllowPaging="true"
        OnPageIndexChanging="OnPageIndexChanging" PageSize="10" UseAccessibleHeader="True" CssClass="table table-hover">
        <Columns>
            <asp:BoundField DataField="EventUserId" HeaderText="User ID" />
            <asp:BoundField DataField="EventDate" HeaderText="Date IN" />
            <asp:BoundField DataField="EventTime" HeaderText="Time IN" />
            <asp:BoundField DataField="Eventtype" HeaderText="Type" />
            <asp:BoundField DataField="Readerid" HeaderText="Reader" />
        </Columns>
    </asp:GridView>     
    </div>

我的存储过程是：

CREATE procedure userSearch
(
@EventUserId int = NULL,
@EventDateFrm nvarchar(10) = NULL,
@EventDateTo nvarchar(10) = NULL,
@Readerid int = NULL
)
as
select V_EventLogs.EventUserId,V_EventLogs.EventDate,V_EventLogs.EventTime,V_EventLogs.Eventtype,V_EventLogs.Readerid 
from V_EventLogs 
where
(@EventUserId is NULL OR EventUserId = @EventUserId )
AND
(@EventDateFrm is NULL OR Convert(varchar(10),EventDate,110) >= Convert(varchar(10),@EventDateFrm,110))
AND 
(@EventDateTo is NULL OR Convert(varchar(10),EventDate,110)  <= Convert(varchar(10),@EventDateTo,110))
AND
(@Readerid is NULL OR Readerid = @Readerid)

现在，当我想搜索员工时，网格数据表仍然是空的，没有得到任何值，但当在SQL server上测试我的存储过程时，它运行良好-第二个问题是，当分页数据表时，动态搜索只对第一个页面有效。当我选择任何其他页面时，搜索实现都不起作用，数据表显示所有数据库值！！为什么？