Microsoft KB Archive/309158

= How To Read and Write BLOB Data by Using ADO.NET with Visual C# .NET =

Article ID: 309158

Article Last Modified on 7/14/2004

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APPLIES TO


 * Microsoft ADO.NET 1.1
 * Microsoft ADO.NET 1.0
 * Microsoft Visual C# .NET 2003 Standard Edition
 * Microsoft Visual C# .NET 2002 Standard Edition

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This article was previously published under Q309158



For a Microsoft Visual Basic .NET version of this article, see 308042.

For a Microsoft Visual J# .NET version of this article, see 320629.

This article refers to the following Microsoft .NET Framework Class Library namespaces:
 * System.Data.SqlClient
 * System.IO

IN THIS TASK
SUMMARY
 * Requirements
 * Create the Project



SUMMARY
The GetChunk and the AppendChunk methods are not available in ADO.NET on DataReader columns, DataSet columns, or Command parameters. This article describes how to use Visual C# .NET to read and write binary large object (BLOB) fields.

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Requirements
The following list outlines the recommended hardware, software, network infrastructure, and service packs that are required:
 * Microsoft Windows 2000 Professional, Windows 2000 Server, Windows 2000 Advanced Server, or Windows NT 4.0 Server
 * Microsoft Visual Studio .NET
 * Microsoft SQL Server

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Create the Project
 Add a table named MyImages to your SQL Server Northwind database. Include the following fields in your table:  Identity field that is named &quot;ID&quot; of type Int. Field that is named &quot;Description&quot; of type VarChar with a length of 50. Field that is named &quot;ImgField&quot; of type Image.

 Start Visual Studio .NET, and then create a new Visual C# Windows Application project. Drag two Button controls from the toolbox to the default form, Form1.</li> In the Properties window, change the Text property of Button1 to Save to Database (from File), and then change the Text property of Button2 to Save to File (from Database) .</li>  Add the following code to the top of the Code window: using System.Data; using System.Data.SqlClient; using System.IO; </li>  Double-click Button1, and then add the following code to the Button1_Click event handler.

Note Uid must have permissions to perform these operations on the database. { SqlConnection con = new SqlConnection(&quot;Server=Darkover;uid= ;pwd= ;database=northwind&quot;); SqlDataAdapter da = new SqlDataAdapter(&quot;Select * From MyImages&quot;, con); SqlCommandBuilder MyCB = new SqlCommandBuilder(da); DataSet ds = new DataSet(&quot;MyImages&quot;);

da.MissingSchemaAction = MissingSchemaAction.AddWithKey; FileStream fs = new FileStream(@&quot;C:\winnt\Gone Fishing.BMP&quot;, FileMode.OpenOrCreate, FileAccess.Read); byte[] MyData= new byte[fs.Length]; fs.Read(MyData, 0, System.Convert.ToInt32(fs.Length)); fs.Close; da.Fill(ds,&quot;MyImages&quot;); DataRow myRow; myRow=ds.Tables[&quot;MyImages&quot;].NewRow;

myRow[&quot;Description&quot;] = &quot;This would be description text&quot;; myRow[&quot;imgField&quot;] = MyData; ds.Tables[&quot;MyImages&quot;].Rows.Add(myRow); da.Update(ds, &quot;MyImages&quot;);

con.Close; }                   </li>  Double-click Button2, and then add the following code to the Button2_Click event handler.

Note Uid must have permissions to perform these operations on the database. { SqlConnection con = new SqlConnection(&quot;Server=Darkover;uid= ;pwd= ;database=northwind&quot;); SqlDataAdapter da = new SqlDataAdapter(&quot;Select * From MyImages&quot;, con); SqlCommandBuilder MyCB = new SqlCommandBuilder(da); DataSet ds = new DataSet(&quot;MyImages&quot;);

byte[] MyData= new byte[0]; da.Fill(ds, &quot;MyImages&quot;); DataRow myRow; myRow=ds.Tables[&quot;MyImages&quot;].Rows[0]; MyData = (byte[])myRow[&quot;imgField&quot;]; int ArraySize = new int; ArraySize = MyData.GetUpperBound(0);

FileStream fs = new FileStream(@&quot;C:\winnt\Gone Fishing2.BMP&quot;, FileMode.OpenOrCreate, FileAccess.Write); fs.Write(MyData, 0,ArraySize); fs.Close; }                   </li> Press F5 to compile and to run the application.</li> Click Save to Database (from File) to load the image, C:\WinNT\Gone Fishing.bmp, into the SQL Server Image field.</li> Click Save to File (from Database) to save the data from the SQL Server Image field back to a file.</li></ol>

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Keywords: kbhowtomaster kbio kbsqlclient kbsystemdata KB309158

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