Comment by rramadass
1 year ago
Not quite true - https://en.wikipedia.org/wiki/Table_(database)#Tables_versus...
A Table is a Relation encoded as a set of tuples resulting from the cartesian product of values from multiple sets each of which is from a domain.
Tables are a weaker form of Relations and hence a superset except for the "ordering" characteristic when it can be considered a subset.
> 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.
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