As Jochen said, this isn't a good question for this forum. Especially the part about using a database - you should just read some articles here on CodeProject, there are many.
However, here are your options for reading from a barcode scanner:
1) A USB-barcode scanner will have keyboard emulation. Meaning, a scanned barcode will appear at your current input cursor as if you've typed the number/string manually into a keyboard. So you could just have a text input control and just don't bother if it's a keyboard or barcode scanner where the input comes from. Advantage: Easiest to set up. Disadvantage: You have to take care that the text input control always has the input focus when the user might want to scan a barcode.
2) The manufacturer of your barcode scanner MIGHT have an API for it. For low budget scanners there are most often none. Advantage: No trouble with an input control. Disadvantage: You're limiting your application to one type (or certain types) of barcode scanner. More work than for 1)
3) Use the Windows "Raw Input API". Explained and demonstrated in this CodeProject article:
Using Raw Input from C# to handle multiple keyboards[
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Advantage: No trouble with an input control. No trouble with vendor specific API's. Disadvantage: More work than for 1)
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