SQL CONVERT from varbinary to varchar

I'm using a C# application and it looks like its ready to insert the image to my database, but my stored procedure spits out an implicit conversion error. I read the image into a byte array and pass the byte array to my stored procedure. It expects a varbinary parameter, hence the error. So I alter my stored procedure to be:

ALTER PROCEDURE insertPlayerImage 
      @playerID varchar(9), 
      @profileImage varchar(max), 
      @pending char(1)
AS
    CONVERT(varbinary(max), @profileImage)

INSERT INTO PlayerImage(playerID, profileImage, pending)
VALUES(@playerID, @profileImage, @pending)
GO

which tells me it expects a varchar (my byte array) and convert the array to a varbinary file. Well my stored procedure doesn't like the the convert line i have. but if I simply do

SELECT CONVERT(varchar, GETDATE());

it works. All google searches point back to converting the date, almost as if its the only thing you can use a convert on.

Solution

Are you using SQL Server? If so, see this page for the SQL data type to CLR data type mappings: http://msdn.microsoft.com/en-us/library/cc716729.aspx

SQL Server char, varchar, nchar and nvarchar all map to/from a C# string (though a char[] will work as well).

SQL Server binary andvarbinarymap to/from a C#byte[]`.

What's the actual problem you're having?

Further, if you're passing binary data as a varchar to SQL Server, I would expect it to get munged in the tranformation between UTF-16 (CLR internal string encoding) to whatever code page SQL Server is using.

Another thing to note: your stored procedure:

ALTER PROCEDURE insertPlayerImage 
  @playerID varchar(9), 
  @profileImage varchar(max), 
  @pending char(1)
AS

  CONVERT(varbinary(max), @profileImage)

  INSERT INTO PlayerImage
  ( playerID , profileImage , pending )
  VALUES
  ( @playerID , @profileImage , @pending )

GO

isn't legal SQL. Convert() is a function, not a SQL statement. It doesn't even compile. If you are trying to convert your varchar parameter @profileImage to varbinary, you're going to have to do something along the lines of

 declare @image varbinary(max)
 set @image = convert(varbinary(max),@profileImage)

If you're stored procedure has the signature

create procedure dbo.insertPlayerImage

  @playerId     varchar(9) ,
  @profileImage varbinary(max) ,
  @pending      char(1)

as
...

Then this code will do you:

public int insertProfileImage( string playerId , byte[] profileImage , bool pending )
{
  if ( string.IsNullOrWhiteSpace(playerId) ) throw new ArgumentException("playerId" ) ;
  if ( profileImage == null || profileImage.Length < 1 ) throw new ArgumentException("profileImage") ;

  int rowCount ;

  string connectString = GetConnectString() ;
  using ( SqlConnection connection = new SqlConnection(connectString) )
  using ( SqlCommand command = connection.CreateCommand() )
  {

    command.CommandType = CommandType.StoredProcedure ;
    command.CommandText = "dbo.insertPlayerImage" ;

    command.Parameters.AddWithValue( "@playerId"     , playerId            ) ;
    command.Parameters.AddWithValue( "@profileImage" , profileImage        ) ;
    command.Parameters.AddWithValue( "@pending"      , pending ? "Y" : "N" ) ;

    rowCount = command.ExecuteNonQuery() ;

  }

  return rowCount ;
}

If however, you're passing a null for image data, you'll need to change how the value of the parameter gets set. Something along the lines of:

command.Parameters.AddWithValue( "@profileImage" , profileImage != null ? (object)profileImage : (object)DBNull.Value ) ;

SqlParameter p = new SqlParameter( "@profileImage" , SqlDbType.VarBinary ) ;
p.Value = DBNull.Value ;
if ( profileImage != null )
{
  p.Value = profileImage ;
}
command.Parameters.Add( p ) ;