C#Winform 在DataGridView（SQL Server）中下载和上传文件方法

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下载方法：

  private void DownloadFile(string gl_fileid)        {            string sql = "select * from files where fileid='" + gl_fileid + "'";            DataTable dt = DBUtil.GetData(sql);            if (dt.Rows.Count > 0)            {                DataRow dr = dt.Rows[0];                string extension = dr["filetype"].ToString();                string filename = dr["filename"].ToString();                byte[] bytes = (byte[])dr["filecontent"];                SaveFileDialog dia = new SaveFileDialog();                dia.FileName = filename;                if (dia.ShowDialog()==DialogResult.OK)                {                    string filePath = dia.FileName;                    FileStream fs = new FileStream(filePath, FileMode.Create, FileAccess.Write);                    fs.Write(bytes, 0, (int)bytes.Length);                    fs.Dispose();                    fs.Close();                    MessageBox.Show("文件下载成功！");                }            }        }

上传方法：

 private void btnSubmit_Click(object sender, EventArgs e)        {            string filePath = this.txtFilePath.Text.ToString();            //Console.WriteLine("filePath"+filePath);            if (filePath.Length == 0)            {                MessageBox.Show("请选择要上传的文件!");                return;            }            string _fileid = Guid.NewGuid().ToString();            string _filename = filePath.Substring(filePath.LastIndexOf("\\") + 1);            string _filetype = _filename.Substring(_filename.LastIndexOf(".") + 1);            string _createtime = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");            string sql = "insert into files(fileid,filename,filetype,filecontent,createtime) values(@fileid,@filename,@filetype,@filecontent,@createtime)";            SqlParameter p_fileid = new SqlParameter("fileid", _fileid);            SqlParameter p_filename = new SqlParameter("filename", _filename);            SqlParameter p_filetype = new SqlParameter("filetype", _filetype);            SqlParameter p_createtime = new SqlParameter("createtime", _createtime);            SqlParameter p_filecontent = new SqlParameter("filecontent", SqlDbType.Image);            FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);                        byte[] bytes = new byte[fs.Length];            fs.Read(bytes, 0, (int)fs.Length);            p_filecontent.Value = bytes;            using (SqlConnection conn = new SqlConnection(sqlconn))            {                conn.Open();                SqlCommand cmd = new SqlCommand();                cmd.Connection = conn;                cmd.CommandText = sql;                cmd.Parameters.Add(p_fileid);                cmd.Parameters.Add(p_filename);                cmd.Parameters.Add(p_filecontent);                cmd.Parameters.Add(p_filetype);                cmd.Parameters.Add(p_createtime);                cmd.ExecuteNonQuery();            }            fs.Close();            fs.Dispose();            MessageBox.Show("文件上传成功！");            this.LoadData();        }

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