Databases · Junior · Question 24 of 75

What does a `CROSS JOIN` of a table with 10 rows and a table with 5 rows return?

✓Correct answer: 50 rows: every combination of rows
25 rows
315 rows

Explanation

It's the Cartesian product. Forgetting the ON condition in older comma-style joins (FROM a, b) accidentally produces the same explosion of rows.

Further reading

PostgreSQL: Table expressions (FROM, JOIN, WHERE, GROUP BY) ↗

Test yourself

Take the Databases · Junior quiz: questions and options are shuffled, and you get a review of your mistakes at the end.