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| [WD20] Unique Key, Duplicates, Null |
| Iniciado por guest, 04,sep. 2015 21:13 - 2 respuestas |
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| Publicado el 04,septiembre 2015 - 21:13 |
| Is it possible to have a unique key(not primary) that doesn't accept duplicates, but does accept unlimited NULL values? If so, how? |
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| Publicado el 04,septiembre 2015 - 21:31 |
Hi Curtis
not that I know off, no...
Best regards |
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| Publicado el 05,septiembre 2015 - 09:32 |
| Hi, no, this is not possible with HFSQL - though good old Btrieve (then Novell, now the core of Pervasive PSQL) had that feature already 25 years ago! Quite some years ago, I had an interesting discussion about this with a PC Soft engineer ... but I think they did not implement this great feature because of fearing to become off SQL-standards. I think you have to resort to a key with duplicates and make programmatically sure that - except for the empty keys - only unique key values are to be added. In your case, barcode values should have a check-number anyway which has to be checked while inputting them. Are these standard 8/13 characters GLN / ILN / GTIN ? |
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