SQL Server: What is the difference between CROSS JOIN and FULL OUTER JOIN?

Question

What is the difference between CROSS JOIN and FULL OUTER JOIN in SQL Server?

Are they the same, or not? Please explain. When would one use either of these?

Answer 1

Cross join :Cross Joins produce results that consist of every combination of rows from two or more tables. That means if table A has 3 rows and table B has 2 rows, a CROSS JOIN will result in 6 rows. There is no relationship established between the two tables – you literally just produce every possible combination.

Full outer Join : A FULL OUTER JOIN is neither "left" nor "right"— it's both! It includes all the rows from both of the tables or result sets participating in the JOIN. When no matching rows exist for rows on the "left" side of the JOIN, you see Null values from the result set on the "right." Conversely, when no matching rows exist for rows on the "right" side of the JOIN, you see Null values from the result set on the "left."