C#中从数据库下载文件

首先要把数据库里面对应的那个字段读出来 然后进行处理

下面的例子是我从数据库读取图片的

OracleConnection conn = new OracleConnection(connstring)

conn.Open()

label1.Text = "开始时间：" + DateTime.Now

string begin = "数据库连接正常,开始时间" + DateTime.Now

SetInfo("", begin)

string SQL = "select ID from bs_buylicense_attach t where t.file_size>204800 order by t.file_size asc" //rownum<100 and

string ConnString = SQL

OracleDataAdapter sda = new OracleDataAdapter(ConnString, conn)

DataTable table = new DataTable()

sda.Fill(table)

List<object>lst = ModelConvertHelper.DtCovertIList(table)

foreach (object o in lst)

{

string path = "C:\\1.png"

string lst_ID = o.ToString() //查询返回来对应的数据的ID

string filter = "select * from bs_buylicense_attach where ID='" + lst_ID + "'"

OracleCommand cmd = new OracleCommand(filter, conn)

OracleDataReader reader = cmd.ExecuteReader()

while (reader.Read())

{

if (reader["DATA"] != DBNull.Value)

{

string ID = "数据ID对应值ID" + reader["ID"].ToString()

string length = "原文件大小" + reader["FILE_SIZE"].ToString()

SetInfo(ID, length)

System.IO.MemoryStream stream = new System.IO.MemoryStream((byte[])reader["DATA"])//把照片读到MemoryStream里

Image ImageBlob = Image.FromStream(stream, true) //从数据库中读到的图片

int height = ImageBlob.Height //原来图片的高度

int width = ImageBlob.Width//原来图片的宽度

//开始进行图片的压缩

GetPicThumbnail1(ImageBlob, path, height, width, 60)

Image SaveImage = im//得到返回来压缩之后的图片

byte[] buffer = imageToByteArray(SaveImage)

string UpdateSql = "update bs_buylicense_attach set DATA =:image where ID='" + lst_ID + "'"

OracleCommand cd = new OracleCommand()

cd = new OracleCommand(UpdateSql, conn)

cd.CommandText = UpdateSql

cd.Parameters.Add("image", System.Data.OracleClient.OracleType.Blob, buffer.Length).Value = buffer

cd.ExecuteNonQuery()

FileStream file = new FileStream(path, FileMode.Open, FileAccess.Read)

string YAsuo = Convert.ToString(file.Length)

SetInfo("压缩为：", YAsuo)

stream.Close()

stream.Dispose()

file.Dispose()

file.Close()

File.Delete(@path)

}

}

}

conn.Close()

string end = "所有数据执行完毕关闭数据库链接！" + DateTime.Now

SetInfo("", end)

SaveLog()

label2.Text = "结束时间：" + DateTime.Now

}

如果你的2010版不是官网的，建议到官网下载一个QQ2011的安装文件后安装。至于用户文件目录可以在主面板的设置--基本设置--文件记录 中设置。QQ用不了不要着急，重装新正式版可以解决很多问题。

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