I am having trouble selecting binary data from a MySQL database using the C API and writing it to a file. I believe I figured out inserting binary data, but I can't verify that until I can select it and write it to a file. Any help or examples would be appreciated. Thanks

What problems are you having exactly?

What function do I use to read the binary data out of the field? Do I use a strcpy to copy data from row[0]? I guess I am looking for the function to retrieve the data from the row and to copy it into my buffer. I am new to the MySQL C API and this is a tough topic to find even using Google.

Thanks,

Pete

Is this any help?

http://www.ousob.com/miscdocs/mysqlapi.htm

I have already looked at that document, thanks though. I guess what I am looking for is the function that will return the binary data after I do a select. All I want to do is get the binary data into a buffer that I have malloced. I can't find any examples of this on the web.

It's been a long time since I've played with the C api but I thought you handled binary data the same way you handled zero padded strings. Just that in this case, you must call mysql_fetch_lengths (as strlen misbehaves) and then do a memcpy into your new struct with the given value.

Okay easy enough, do you know what my src would be for the memcpy?

Does this help?

http://www.mkssoftware.com/docs/man3/memcpy.3.asp

Just a note, if this is going to be a public C application, I'd say watch out. You're venturing to the world of buffer overflow attacks and unless you're quite experienced it may be better to do this in something like perl instead.

I understand memcpy, I am just wondering what src I am copying from (i.e. where is the binary data I am trying to copy?). memcpy(dst, src????, size). I don't see where I can get access to the binary data to copy it. Maybe I am just not understanding something. No this isn't a public application, just me messing around with the MySQL C API and brushing up on my C skills so it's not a big deal, just doing this for heck of it.

You may want to take a look at the bottom of this document.

http://www.ousob.com/miscdocs/mysqlapi.htm