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    <p>When you say “open as a PDF”, I assume that you mean that you want some external program to see the data as a file? The only ways to do that are either:</p> <ol> <li>Do some clever shenanigans with user-mode filesystems on Linux (or the equivalent on your OS) so that the database can be actually mounted, or</li> <li>Copy the data from the database into a temporary file with the right name (hint: keep that as a separate column in that table).</li> </ol> <p>There's also presenting it all as a webserver, but that's really the second with a browser in the mix; the data is still copied.</p> <p>On the other hand, if all you want to do is have the data as a stream that you can read or write from Tcl, the sqlite3 package has what you need:</p> <pre><i>dbcmd</i> <b>incrblob</b> ?<b>-readonly</b>? ?<i>db</i>? <i>table column rowid</i></pre> <p>Which returns a standard channel handle (though not one backed up by an OS handle, so be careful if using as a redirection with <code>exec</code>).</p> <hr> <p>[EDIT]: Here's how to getthe data out (replace <code>...</code> with a clause to get the right row, of course):</p> <pre><code># Open the DB sqlite3 db Docs.db # Open the file to write to set fileID [open $fileText w] fconfigure $fileID -translation binary # Write the BLOB db eval {SELECT Doc FROM Document WHERE ... LIMIT 1} row { puts -nonewline $fileID $row(Doc) } # We're done! close $fileID db close </code></pre> <p>Don't worry about the size of the BLOB; the Tcl <code>sqlite3</code> package passes it around efficiently. If you're still concerned, here's the other way (again, you'll need to replace <code>...</code> appropriately):</p> <pre><code># Open the DB sqlite3 db Docs.db # Open the file to write to set fileOut [open $fileText w] fconfigure $fileOut -translation binary # Get the BLOB as a (read-only) channel set fdBlob [db incrblob -readonly Document Doc ...] fconfigure $fdBlob -translation binary # Do the copy fcopy $fileOut $fdBlob # We're done! close $fdBlob close $fileOut db close </code></pre>
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    1. COHi Donald - thanks for your feedback. I was hoping to develop a tcl tk frontend that would allow an end user to upload a pdf file (to sqlite), and then be able to download the pdf for usage, like a standard file database. The upload part seems simple enough, using binary/blob data. I might be doing something wrong. Is opening a i/o channel my only option with blob data or can the data be opened as a file, similar to opening a file from a web driven Db?
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    2. CO@DFM: SQLite keeps the BLOB in the database, so opening it as a file directly isn't going to work (well, not without egregious hacks as in point 1 of my answer). Copy it out. NB: copying out is only a few lines of code.
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    3. COHi Donald - Copying the data out works well. As a test, instead of puts..., I copied it out to a text box widget, since I am not using a shell. I found that copying out pdf or Word doc blob data gives me unrecognized characters, most likely because of the format. How would I compile this data back into a pdf or Word doc?
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