copying gridview data from one form to another form's gridview

protected void Page_Load(object sender, EventArgs e)
{
    Calendar1.Visible = false;
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    SqlConnection con = new SqlConnection("connection string");
    con.Open();
    DataTable dt = new DataTable();
    SqlCommand sqlCmd = new SqlCommand("SELECT distinct plantname,operatorname FROM datalogging1 WHERE Line='" + ddlline.SelectedItem + "'and date='"+txtdate.Text+"'and shiftname='"+ddlshift.SelectedItem+"'", con);
    SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd);
    sqlDa.Fill(dt);

    if (dt.Rows.Count > 0)
    {
        //Where ColumnName is the Field from the DB that you want to display 
        txtplant.Text = dt.Rows[0]["Plantname"].ToString();
        txtop.Text = dt.Rows[0]["operatorname"].ToString();

    }
}
protected void btndate_Click(object sender, EventArgs e)
{
    Calendar1.Visible = true;
}
protected void Calendar1_SelectionChanged(object sender, EventArgs e)
{
    txtdate.Text = Calendar1.SelectedDate.ToString("yyyy/MM/dd");
}
protected void btnreport_Click(object sender, EventArgs e)
{
    int var = ddlshift.SelectedIndex;
    switch (var)
    {
        case 0:
            break;
        case 1: SqlConnection con1 = new SqlConnection("connection string");
            con1.Open();
            DataTable dt = new DataTable();
            SqlCommand cmd1 = new SqlCommand("select Date=convert(varchar(12),isnull(t1.date,t2.date),101),Time=convert(varchar(8),isnull(t1.time,t2.time),8),isnull(t1.temprature,0) as Temperature,isnull(t2.pressure,0) as Pressure,isnull(t3.co2,0) as Co2,isnull(t4.do2,0) as Do2,isnull(t5.ph,0) as pH,isnull(t6.speed,0) as Speed,isnull(t7.flow,0) as Flow from temprature3 t1 full outer join pressure3 t2 on t2.date=t1.date and t1.time=t2.time full outer join co23 t3 on t1.date=t3.date and t1.time=t3.time full outer join do23 t4 on t1.date=t4.date and t1.time=t4.time full outer join ph3 t5 on t1.date=t5.date and t1.time=t5.time full outer join speed3 t6 on t1.date=t6.date and t1.time=t6.time full outer join flow3 t7 on t1.date=t7.date and t1.time=t7.time where t1.Date='"+txtdate.Text+"' and t1.time between '1900-01-01 7:00:00.000' and '1900-01-01 12:59:59.999'", con1);
            SqlDataAdapter da1 = new SqlDataAdapter(cmd1);
            da1.Fill(dt);
            GridView1.Visible = true;
            GridView1.DataSource = dt;
            GridView1.DataBind();
            break;
 开发者_JAVA技巧       case 2:
            SqlConnection con2 = new SqlConnection("connection string");
            con2.Open();
            DataTable dt1 = new DataTable();
            SqlCommand cmd2 = new SqlCommand("select Date=convert(varchar(12),isnull(t1.date,t2.date),101),Time=convert(varchar(8),isnull(t1.time,t2.time),8),isnull(t1.temprature,0) as Temperature,isnull(t2.pressure,0) as Pressure,isnull(t3.co2,0) as Co2,isnull(t4.do2,0) as Do2,isnull(t5.ph,0) as pH,isnull(t6.speed,0) as Speed,isnull(t7.flow,0) as Flow from temprature3 t1 full outer join pressure3 t2 on t2.date=t1.date and t1.time=t2.time full outer join co23 t3 on t1.date=t3.date and t1.time=t3.time full outer join do23 t4 on t1.date=t4.date and t1.time=t4.time full outer join ph3 t5 on t1.date=t5.date and t1.time=t5.time full outer join speed3 t6 on t1.date=t6.date and t1.time=t6.time full outer join flow3 t7 on t1.date=t7.date and t1.time=t7.time where t1.Date='" + txtdate.Text + "' and t1.time between '1900-01-01 13:00:00.000' and '1900-01-01 22:59:59.999'", con2);
            SqlDataAdapter da2 = new SqlDataAdapter(cmd2);
            da2.Fill(dt1);
            GridView1.Visible = true;
            GridView1.DataSource = dt1;
            GridView1.DataBind();
            break;
        case 3: SqlConnection con3 = new SqlConnection(""connection string);
            con3.Open();
            DataTable dt2 = new DataTable();
            SqlCommand cmd3 = new SqlCommand("select Date=convert(varchar(12),isnull(t1.date,t2.date),101),Time=convert(varchar(8),isnull(t1.time,t2.time),8),isnull(t1.temprature,0) as Temperature,isnull(t2.pressure,0) as Pressure,isnull(t3.co2,0) as Co2,isnull(t4.do2,0) as Do2,isnull(t5.ph,0) as pH,isnull(t6.speed,0) as Speed,isnull(t7.flow,0) as Flow from temprature3 t1 full outer join pressure3 t2 on t2.date=t1.date and t1.time=t2.time full outer join co23 t3 on t1.date=t3.date and t1.time=t3.time full outer join do23 t4 on t1.date=t4.date and t1.time=t4.time full outer join ph3 t5 on t1.date=t5.date and t1.time=t5.time full outer join speed3 t6 on t1.date=t6.date and t1.time=t6.time full outer join flow3 t7 on t1.date=t7.date and t1.time=t7.time where t1.Date='" + txtdate.Text + "' and t1.time between '1900-01-01 23:00:00.000' and '1900-01-01 6:59:59.999'", con3);
            SqlDataAdapter da3 = new SqlDataAdapter(cmd3);
            da3.Fill(dt2);
            GridView1.Visible = true;
            GridView1.DataSource = dt2;
            GridView1.DataBind();
            break;
    }
}
public void ExportGridToExcel(GridView grdGridView, string fileName)
{
    Response.Clear();
    Response.AddHeader("content-disposition",
        string.Format("attachment;filename={0}.xls", fileName));
    Response.Charset = "";
    Response.ContentType = "application/vnd.xls";

    StringWriter stringWrite = new StringWriter();
    HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
    grdGridView.RenderControl(htmlWrite);
    Response.Write(stringWrite.ToString());
    Response.End();
}
public override void VerifyRenderingInServerForm(Control control)
{
    /* Verifies that a Form control was rendered */
}

protected void Button1_Click(object sender, EventArgs e)
{
    ExportGridToExcel(GridView1, "report.xls");
}

Since you have not provided the code, we can't figure out the issue.

But the code below works perfectly to Export GridView data to Excel, you can use this code.

public void ExportGridToExcel(GridView grdGridView, string fileName)
{
Response.ClearContent();    
Response.AddHeader("content-disposition",
    string.Format("attachment;filename={0}.xls", fileName));
Response.ContentType = "application/vnd.xls";

StringWriter stringWrite = new StringWriter();
HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
grdGridView.RenderControl(htmlWrite);
Response.Write(stringWrite.ToString());
Response.Flush();
Response.End();
}