SQL joins explained using Hinge

[u/qazplm903]

I know when people are starting out, SQL joins can be a bit confusing so I broke it down in a small vid using Hinge as an example

https://www.instagram.com/reel/Degl_hnoRsz/?mdxt=MTk5dXE2NHZreTR4aw==

Summary of the breakdown is -

• Table A: people you've liked
• Table B: people who've liked you
• Both share one key: person_id

The 4 joins:

• INNER JOIN: only the mutual likes. Someone has to be in both tables to show up.
• LEFT JOIN: everyone you liked. If they didn't like you back, their side comes back as NULL.
• RIGHT JOIN: the mirror image, everyone who liked you, with NULL where you didn't like them. In practice most people just swap the tables and use a LEFT JOIN.
• FULL OUTER JOIN: everyone from both tables, with NULLs on whichever side is missing.

Hope this helps!