ASP.NET 上传图片至数据库并读取图片显示

<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />

<td>
<img id="imghead"  runat="server" src='../images/noimg.gif'>
</td>

<td>
相关图片:
</td>

<td>
<%-- <asp:FileUpload ID="FileUpload1" runat="server" onchange="previewImage(this)" ></asp:FileUpload>--%>
<asp:FileUpload ID="FileUpload1" runat="server" />
<%--<hr />
<asp:Label ID="LabMessage1" runat="server" ForeColor="red" /><br />
<asp:Label ID="LabMessage2" runat="server" />--%>

</td>

public string _path = "";

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
if (Request.QueryString["key"] != null)
{
string sql = "select * from ChiH_Material where id=" + Request.QueryString["key"].ToString();
DataTable dt = bc.ReadTable(sql);
if (dt.Rows.Count > 0)
{
imghead.Src = dt.Rows[0]["picture"].ToString();

}

}
else
{
}
}
}

protected void Button1_Click(object sender, EventArgs e)
{
try
{
uploadfile2();

if (Request.QueryString["key"] != null)
{
string sql = "update ChiH_Material set inside_model='" + inside_model.Value.Trim() + "',model='" + model.Value.Trim() + "',high_flower='" + high_flower.Value.Trim() + "',breadth='" + breadth.Value.Trim() + "',Stock='" + Stock.Value.Trim() + "',go_code='" + go_code.Value.Trim() + "',product_price='" + product_price.Value.Trim() + "',Grey_price='" + Grey_price.Value.Trim() + "',remark='" + remark.Value.Trim() + "',picture='" + _path + "' where id=" + Request.QueryString["key"].ToString();
bc.execsql(sql);

}
else
{
string sql = "insert into ChiH_Material(inside_model,sup_no,model,high_flower,breadth,Stock,go_code,product_price,Grey_price,remark,picture) values('" + inside_model.Value.Trim() + "','" + sup_no.Value.Trim() + "','" + model.Value.Trim() + "','" + high_flower.Value.Trim() + "','" + breadth.Value.Trim() + "','" + Stock.Value.Trim() + "','" + go_code.Value.Trim() + "','" + product_price.Value.Trim() + "','" + Grey_price.Value.Trim() + "','" + remark.Value.Trim() + "','" + _path + "')";
bc.execsql(sql);
}
Response.Write("<script type=\"text/javascript\">alert('保存成功');window.returnValue='ok';window.close();</script>");

}
catch (Exception)
{
Response.Write("<script type=\"text/javascript\">alert('操作失败！');window.returnValue='ok';window.close();</script>");
}
}

public void uploadfile2()
{
bool fileOK = false;
string path = Server.MapPath("../drawimg/");
_path = "../drawimg/" + FileUpload1.FileName;
if (FileUpload1.HasFile)
{
String fileExtension = System.IO.Path.GetExtension(FileUpload1.FileName).ToLower();
String[] allowedExtensions = { ".gif", ".png", ".bmp", ".jpg" };
for (int i = 0; i < allowedExtensions.Length; i++)
{
if (fileExtension == allowedExtensions[i])
{
fileOK = true;
}
}
}
if (fileOK)
{
try
{
FileUpload1.SaveAs(path + FileUpload1.FileName);

//LabMessage1.Text = "文件上传成功.";
//LabMessage2.Text = "<b>原文件路径：</b>" + FileUpload1.PostedFile.FileName + "<br />" +
//              "<b>文件大小：</b>" + FileUpload1.PostedFile.ContentLength + "字节<br />" +
//              "<b>文件类型：</b>" + FileUpload1.PostedFile.ContentType + "<br />";
}
catch (Exception ex)
{
//LabMessage1.Text = "文件上传不成功.";
}
}
else
{
//LabMessage1.Text = "只能够上传图片文件.";
}
}