[EMAIL PROTECTED] wrote:
"David Godsey" <[EMAIL PROTECTED]> wrote on 02/14/2006 03:28:41 PM:
Well, just thought I'd try one more time because I didn't get an answer
to
my question last time.
So what I have is a random data stream that is sent in raw form, and
based
on some data definition, I can assemble with the correct data types and
such. One of my requirements is that I have to store the data in raw
form, and when I pull the data out, it displays based on the
configuration
(with the correct data types and such). So floats and doubles are IEEE
standards so I don't have to worry about those, however with integer
types, I may need to do some byte swapping (because this data can come
from variouse systems that could be either big or little endian). So I
am
singling out the data I need, but now I need to add the ability to byte
swap the data.
Keep in mind that it would be best if I can do this in SQL so that it is
portable. I realize that it can easily be done in C, but that makes my
code less portable (which is also a requirement, to have it portable
that
is). So does anybody know of a MySQL function that is already
implemented
to do byte swapping? or know of a way to implement this in SQL?
If not, is my only other option to write a UDF?
Thanks for any help.
Accomplishing the impossible means only that the boss will add it to
your
regular duties.
David Godsey
Native functions? No. Something you can cobble together? Yes. There
should be several ways you can deal with your data as a string of binary
characters. Just re-sequence those and you should have your bytes swapped.
One idea is to use the substring functions directly on your BINARY string.
Another is to use the substring functions in combination with
HEX()/UNHEX() to work on an escaped version of your BINARY string.
Would not the first zero value character terminate the substring,
rendering it invalid?
Sorry or the lame ideas but usually things like this are not handled at
the database layer but rather in the application layer. Depending on which
version of MySQL you are using you may be able to define a FUNCTION (a
different creature than a UDF) or a STORED PROCEDURE to do the swapping.
Both will be pure SQL and should meet your compatibility needs. Neither
will be as fast as creating and registering a UDF, though.
Shawn Green
Database Administrator
Unimin Corporation - Spruce Pine
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