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Um no. The left and right joins both include the inner join tuples; they are not mutually exclusive. A cross join is the Cartesian product of two sets, which me
by astine 8y ago
Um no. The left and right joins both include the inner join tuples; they are not mutually exclusive. A cross join is the Cartesian product of two sets, which means it doesn't include the outer join tuples.
- shrimpx 8y agoOk I should have been more precise. By "left join tuples" I intended to mean the "left join - inner join" tuples. The point is you can use sets and Venn diagrams to talk about joins.
- astine 8y agoYou're language is still not quite right. A cross product does not include those parts of the outer joins. An inner join is a subset of a cross product, but an outer join includes elements not in either. What you say would be true of a full outer join, but not a cross product. If one circle in the Venn diagram represents the left join and one circle right join, then the Venn diagrams would be correct but not if the circles represent separate tables.