You want to use the camera in the iPad to scan a bar code, then automatically find the matching data record in the spreadsheet?
There are apps that may do what you need, but perhaps not exactly in the way you envision - you'll have to read the descriptions and perhaps spend a few dollars to try them out.
I searched the App Store for "spreadsheet bar code" and found several apps designed for inventory management that will create a new spreadsheet file that you can export. I also found one that may be what you're looking for "Csv File Editor with Import Option from Excel..." What's not clear to me is whether it will automatically search the spreadsheet, or whether you'd have to copy the code and paste it into the spreadsheet search feature.
There may be another way to approach this, which is to use an app like Workflow. With that, you may be able to create a single script (sequence of steps) that you can run as if it was a single app - scan the bar code with a bar code app, copy the number to the clipboard, switch to the spreadsheet app, paste the bar code into the spreadsheet search, and execute the search.
