I need a condition, that checks a duplicate number in the given exhibition. The number should be unique for an unique exhibition, but the number could appear in another exhibition again of course.
In other words, the duplicate check should only happen for the current exhibition, where I number the existing and new items (artwork) exhibited in that one exhibition. I don`t care if a number is already existing in another exhibition.
In other words, the duplicate check should only happen for the current exhibition, where I number the existing and new items (artwork) exhibited in that one exhibition. I don`t care if a number is already existing in another exhibition.
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