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다음은 microsoft.public.dotnet.framework.adonet 에 올라왔던 질문과 대답입니다. BLOB 데이터를 읽고 쓰는 것에 대한 내용을 달고 있습니다. Here is some code that uses a buffer for reading and writing blobs to SQL Server (only the reading code is in the docs). This was posted by Doug Rothaus a couple of months ago. -- Andy From: "Doug Rothaus \(MSFT\)" <douglasr@nospam.com> References: <0ba101c17ed1$329f4d50$a4e62ecf@tkmsftngxa06> Subject: Re: Image Column Data In SQL Server Date: Fri, 7 Dec 2001 13:48:01 -0800 Message-ID: <umw0rj2fBHA.848@tkmsftngp03> Here's some sample code that is included in the release documentation for the .NET Frameworks in a topic called "Obtaining BLOB Values from a Database". The code reads bitmaps from the pubs database and writes them to disk. I did a quick test on an Excel file and no problems occurred. See if it works for your situation. As far as writing BLOBs are concerned, there is no topic for the release docs, but I have some working code that writes to SQL Server 2000 that you can review. I'll include it as well. Again, it's hard coded to read a bitmap file. I tested it with Excel as well and no problems occurred. I gathered from your previous posts that you prefer VB.NET. Let me know if you want the C# version. Doug Rothaus douglasr@microsoft.com ------------------------------------------------------ This posting is provided "AS IS" with no warranties, and confers no rights. --- obtaining BLOB values --- Dim pubsConn As SqlConnection = New SqlConnection("Data Source=localhost;Integrated Security=SSPI;Initial Catalog=pubs;") Dim logoCMD As SqlCommand = New SqlCommand("SELECT pub_id, logo FROM pub_info", pubsConn) Dim fs As FileStream ' Writes the BLOB to a file (*.bmp). Dim bw As BinaryWriter ' Streams the binary data to the FileStream object. Dim bufferSize As Integer = 100 ' The size of the BLOB buffer. Dim outbyte(bufferSize - 1) As Byte ' The BLOB byte() buffer to be filled by GetBytes. Dim retval As Long ' The bytes returned from GetBytes. Dim startIndex As Long = 0 ' The starting position in the BLOB output. Dim pub_id As String = "" ' The publisher id to use in the file name. ' Open the connection and read data into the DataReader. pubsConn.Open() Dim myReader As SqlDataReader = logoCMD.ExecuteReader(CommandBehavior.SequentialAccess) Do While myReader.Read() ' Get the publisher id, which must occur before getting the logo. pub_id = myReader.GetString(0) ' Create a file to hold the output. fs = New FileStream("logo" & pub_id & ".bmp", FileMode.OpenOrCreate, FileAccess.Write) bw = New BinaryWriter(fs) ' Reset the starting byte for a new BLOB. startIndex = 0 ' Read bytes into outbyte() and retain the number of bytes returned. retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize) ' Continue reading and writing while there are bytes beyond the size of the buffer. Do While retval = bufferSize bw.Write(outbyte) bw.Flush() ' Reposition the start index to the end of the last buffer and fill the buffer. startIndex = startIndex + bufferSize retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize) Loop ' Write the remaining buffer. bw.Write(outbyte) bw.Flush() ' Close the output file. bw.Close() fs.Close() Loop ' Close the reader and the connection. myReader.Close() pubsConn.Close() --- end obtaining BLOB values --- --- writing BLOB values --- Imports System Imports System.Data Imports System.Data.SqlClient Imports System.IO Public Class ChunkImage Public Shared Sub Main() '* '* CREATE TABLE Images ( '* ImageID int IDENTITY (1, 1) NOT NULL , '* Picture image NULL '* ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] '* GO '* '* ALTER TABLE Images WITH NOCHECK ADD '* CONSTRAINT PK_Images PRIMARY KEY CLUSTERED '* ( '* ImageID '* ) ON [PRIMARY] '* GO '* '''''''''''''''''''''''''''''''''''''' '' Command to insert new image record Dim conn As SqlConnection = New SqlConnection("Data Source=localhost;Integrated Security=SSPI;Initial Catalog=Test;") Dim AddImage As SqlCommand = New SqlCommand("INSERT INTO Images (Picture) Values(0x0);" & _ "SELECT @Identity = SCOPE_IDENTITY();" & _ "SELECT @Pointer = TEXTPTR(Picture) FROM Images WHERE ImageID = @Identity", conn) Dim pointer As SqlParameter = AddImage.Parameters.Add("@Pointer", SqlDbType.Binary, 16) pointer.Direction = ParameterDirection.Output Dim id As SqlParameter = AddImage.Parameters.Add("@Identity", SqlDbType.Int) id.Direction = ParameterDirection.Output '''''''''''''''''''''''''''''''''''''' '' Command to append image data Dim bufferLen As Integer = 128 Dim AppendToImage As SqlCommand = New SqlCommand("UPDATETEXT Images.Picture @Pointer @Offset 0 @Bytes", conn) Dim ptr As SqlParameter = AppendToImage.Parameters.Add("@Pointer", SqlDbType.Binary, 16) Dim img_data As SqlParameter = AppendToImage.Parameters.Add("@Bytes", SqlDbType.Binary, bufferLen) Dim offset As SqlParameter = AppendToImage.Parameters.Add("@Offset", SqlDbType.Int) offset.Value = 0 ''''''''''''''''''''''''''''''''''''' '' Add Image record and retrieve image idenity and pointer conn.Open() AddImage.ExecuteNonQuery() Console.WriteLine("Image added. ImageID = " & id.Value) ptr.Value = pointer.Value 'image pointer '''''''''''''''''''''''''''''''''''' '' Read image in and write to database 128 bytes at a time Dim fileName As string = "logoimage.bmp" Dim fs As FileStream = New FileStream(fileName, FileMode.Open, FileAccess.Read) Dim br As BinaryReader = New BinaryReader(fs) Dim buffer() As Byte = br.ReadBytes(bufferLen) Dim offset_ctr As Integer = 0 Do While buffer.Length > 0 img_data.Value = buffer AppendToImage.ExecuteNonQuery() offset_ctr += bufferLen offset.Value = offset_ctr buffer = br.ReadBytes(bufferLen) Loop conn.Close() br.Close() fs.Close() End Sub End Class --- end writing BLOB values ---
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