Comment by randomdata
1 year ago
> multiple sets
Right. As before, you cannot build a table on top of a relation. You can build a relation on top of a table, though.
> Tables are a weaker form of Relations
Yes, exactly, hence it being a subset.
1 year ago
> multiple sets
Right. As before, you cannot build a table on top of a relation. You can build a relation on top of a table, though.
> Tables are a weaker form of Relations
Yes, exactly, hence it being a subset.
> you cannot build a table on top of a relation
Of course you can; it is in the very definition of the Table which is a manifestation of a Relation. Relationships (which can also be mathematical Relations) across Tables/Views are a different thing.
> hence it being a subset.
No, all Relations are Tables but not all Tables are Relations because of ordering, duplicates, nulls.
> Of course you can; it is in the very definition of the Table which is a manifestation of a Relation.
You said multiple relations earlier, which is what the comment was in reply to. Why the fliply-flopping?
> Relationships
Relation, not relations, not relationships. The struggle is real.
> all Relations are Tables
Yes, that's right, a relation is a table with additional constraints – a superset. Although not a strict superset as it does not carry ordering forward.
You seem to be confused between the mathematical definition of a Relation and the English usage of the word "Relation".
> You said multiple relations earlier, which is what the comment was in reply to. Why the fliply-flopping?
Read my definition above again; I said "multiple sets" and NOT "multiple relations" which is a very different thing. You understood it wrong.
> Relation, not relations, not relationships. The struggle is real.
Only for you. I have been very clear in the usage of my terms above. A Table encodes a Relation. Additionally, when you do a JOIN across Tables you are manifesting a "Relationship" (English usage) which may/may not result in a Mathematical Relation.
> a relation is a table with additional constraints – a superset.
No, If there are additional constraints on set A than on set B then A cannot be a superset of B but a subset.