Timeline for Does 1NF require that there can be no duplicate rows?
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| Jul 7, 2018 at 17:01 | comment | added | Renzo | Having a primary key is independent from the atomicity of attributes. It simply expresses the condition that a relation must be a set. You can have set of tuples with non atomic fields. If you have both, this a definition of the concept of relation in the relational model. | |
| Jul 6, 2018 at 6:07 | comment | added | Tim | Thanks. I have found a book which mentions both being atomic and having a primary key for first normal form. See my update to my post. Does the book imply having a primary key implies being atomic, and is it correct? | |
| Jan 16, 2018 at 8:26 | history | edited | Renzo | CC BY-SA 3.0 |
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| Jan 15, 2018 at 14:36 | history | edited | Renzo | CC BY-SA 3.0 |
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| Jan 15, 2018 at 10:58 | history | edited | Renzo | CC BY-SA 3.0 |
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| Jan 14, 2018 at 23:22 | comment | added | Derek Elkins left SE | I would shift the emphases a bit. As you say, duplicates are not allowed in the relational model because we're talking about relations, so it's not so much 1NF that requires this, but the use of the relational model itself. I would view things like the Nested Relational Calculus (NRC) which allows relation-valued attributes as being reasonably "relational" but allowing violations of 1NF. If you view the relational model set-theoretically, then NRC is a perfectly fine relational model. If you view it logically, it's the distinction between a first-order and a higher-order logic. | |
| Jan 14, 2018 at 22:14 | history | edited | Renzo | CC BY-SA 3.0 |
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| Jan 14, 2018 at 22:09 | history | answered | Renzo | CC BY-SA 3.0 |