Subject Re: [firebird-support] Re: Field for BarCode
Author Helen Borrie
At 05:34 AM 25/07/2003 +0000, you wrote:
>Thanks to everyone who replied about this issue.
>I'm glad to hear blob's aren't needed.
>I honestly wasn't sure.
>I know the next questions are a touch off topic, but they are
>somewhat relevant to my FB database.
>Because they are stored in CHAR fields (or VARCHAR) I'll obviously
>need to know the size of the barcode data.
>Who determines the symbologies?

It all depends on the symbologies your application needs to support. Each
main group of symbologies has its own set of rules about how the barcodes
are calculated. Then, at national and international levels, there are
standards that say what symbologies are used for what, allocate groups of
codes to specific industries, etc. etc. (This is a gross
over-simplification of a huge, interlocking area of technologies and

>Is that something I can determine, or is it up to the actual scanner

Scanner devices can be programmed to handle specific symbologies, sets and
subsets. There's a variety of technology for doing this, ranging from
software to EProms to SIMM cards (and no doubt more that I don't know
about). Most modern scanners have the intelligence to discern which
symbology (of the ones they are programmed to recognise) they are reading.

From the software end of things, you need to concern yourself with the
length of the string you have to store and, possibly, some routine to
verify that a code is valid (many of the symbologies include checksums for
this). Scanners read barcodes and return strings to your software. You
can install software, components, etc. that take your strings, apply a
symbology algorithm to the strings and output barcodes to your printer.

>Or is it the actual barcodes?

A barcode is just an image representation of the code elements that are
comprised by the string of characters that's stored. There shouldn't ever
be any need to store a barcode as an image, since a barcode printer, or a
printer with a barcode driver, can regenerate any barcode from the stored

You've got some research to do. A good place to start, since you are in
Oz, might be here: