TSQL in Memory VarBinary to Text File?

Question

With SQL Server 2008, I have a stored procedure that accepts a VarBinary parameter. While the parameter is in memory, I would like to write it to the %temp% directory of the SQL Server.

How can I go from memory blob (it came as a byte[] from a C# app) to text file? The blob does not exist in any disk-resident table.

I am leaning towards having the TSQL sproc call a CLR stored procedure, which so far looks (mostly) like the below.

Problem #1 is that I think the inputBytes[] is stuck at 8k input size.

Problem #2 is that I can't seem to come up with some decent SQL that passes a varbinary value as a parameter so I can test this within Management Studio or VS DB unit test.

public static void FileWrite( string inputName , byte[] inputBytes )
using (FileStream fileStream = new    
   FileStream(Environment.GetEnvironmentVariable("TEMP") + "\\" + inputName,   
   FileMode.OpenOrCreate, FileAccess.Write))
   {
        using ( BinaryWriter binaryWriter = new BinaryWriter(fileStream))
        {
           binaryWriter.Write( inputBytes );
    }
}

Thanks.

dana · Answer 1 · 2011-01-13T01:11:36.970

If you have the byte[] in C# code, you could easily write to a file:

http://msdn.microsoft.com/en-us/library/system.io.file.writeallbytes.aspx

Would this work for you?

EDIT: Another idea if you must initiate the file save from SQL Server might be to create a SQL Server CLR Function. This would allow you to execute C# code from SQL Server.

EDIT 2: I did a Google search and found an article on CodeProject. In the article, they are compressing and decompressing blob data. I think the trick here is to use the SqlBytes parameter type vs a plain old byte[]. Below is some (untested) code I came up with after reading the article and your updated question:

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;

using System.IO;
using System.IO.Compression;

public partial class UserDefinedFunctions
{
    // Setting function characteristics
    [Microsoft.SqlServer.Server.SqlFunction(IsDeterministic=true, DataAccess=DataAccessKind.None)]
    public static void fn_WriteToFile(string fileName, SqlBytes blob)
    {
        if( blob.IsNull || String.IsNullOrEmpty(fileName) )
        {
            return;
        }

        String fullFileName = Path.Combine(Environment.GetEnvironmentVariable("TEMP"), fileName);
        using( FileStream fileStream = new  FileStream(fullFileName, FileMode.OpenOrCreate, FileAccess.Write))
        using( BinaryWriter binaryWriter = new BinaryWriter(fileStream) )
        {
            binaryWriter.Write(blob.Buffer);
        }
    }
};

Let me know what you think.

Thanks, while you were pointing me towards a CLR sproc, I was going down that route myself. I can't seem to figure out how to take an unlimited sized VarBinary(Max) and send it to the CLR sproc as a byte[] so I can write it.... Time to edit my original post. Thanks. — Snowy, Jan 12 '11 at 04:15
Dana, that is awesome. The key was the SqlBytes Type. Thanks! — Snowy, Jan 13 '11 at 15:41

TSQL in Memory VarBinary to Text File?

1 Answers1