# Is Cartesian Product same as SQL Full Outer Join?

Is Cartesian Product same as Full Outer Join found in Relational Database SQL? I ask because I am taking a Discrete Mathematics course and I just want a better understanding of how what I am studying (Cartesian Product) applies to or maps to what I do when developing software (SQL Joins).

No: the Cartesian product is not the same as SQL FULL OUTER JOIN.
For example: if A = {1,2} and B = ∅, then A × B = {1,2} × ∅ = ∅, i.e. the Cartesian product yield the empty set. But, since FULL OUTER JOIN does not require each record in the two joined tables to have a matching record, if B is empty and A is not, FULL OUTER JOIN will still return some rows.
However, CROSS JOIN will return the Cartesian product of rows from tables in the join.