从Web页面把SQL导出Excel，如何既保存在服务器端，又能自动导出到客户端。

1、数据表Temp 中关键要建立Id字段并设置为标识主键。

2、引用为

protected void Button1_Click(object sender, EventArgs e)
{
DataTable dt = Connect.BindTable(" SELECT * FROM Temp Order by Id Desc");
Export(this, dt, this.tbValidTime.Text + '-' + this.tbEnd.Text + "在线统计报表.xls");
}

3、定义

public static void Export(System.Web.UI.Page page, System.Data.DataTable tab, string FileName) //Book1.xls
{
System.Web.HttpResponse httpResponse = page.Response;
System.Web.UI.WebControls.DataGrid dataGrid = new System.Web.UI.WebControls.DataGrid();
dataGrid.DataSource = tab.DefaultView;
dataGrid.AllowPaging = false;
dataGrid.HeaderStyle.BackColor = System.Drawing.Color.Green;
dataGrid.HeaderStyle.HorizontalAlign = HorizontalAlign.Center;
dataGrid.HeaderStyle.Font.Bold = true;
dataGrid.DataBind();
httpResponse.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(FileName, System.Text.Encoding.UTF8)); //filename="*.xls";
httpResponse.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
httpResponse.ContentType = "application/ms-excel";
System.IO.StringWriter tw = new System.IO.StringWriter();
System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
dataGrid.RenderControl(hw);

string filePath = page.Server.MapPath("..") + "//Files//" + FileName;
System.IO.StreamWriter sw = System.IO.File.CreateText(filePath);
sw.Write(tw.ToString());
sw.Close();

DownFile(httpResponse, FileName, filePath);

httpResponse.End();
}

private static bool DownFile(System.Web.HttpResponse Response, string fileName, string fullPath)
{
try
{
Response.ContentType = "application/octet-stream";

Response.AppendHeader("Content-Disposition", "attachment;filename=" +
HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8) + ";charset=GB2312");
System.IO.FileStream fs = System.IO.File.OpenRead(fullPath);
long fLen = fs.Length;
int size = 102400;//每100K同时下载数据
byte[] readData = new byte[size];//指定缓冲区的大小
if (size > fLen) size = Convert.ToInt32(fLen);
long fPos = 0;
bool isEnd = false;
while (!isEnd)
{
if ((fPos + size) > fLen)
{
size = Convert.ToInt32(fLen - fPos);
readData = new byte[size];
isEnd = true;
}
fs.Read(readData, 0, size);//读入一个压缩块
Response.BinaryWrite(readData);
fPos += size;
}
fs.Close();
System.IO.File.Delete(fullPath);
return true;
}
catch
{
return false;
}
}