CROSS JOIN for all combinations


It is the cartesian products of both tables, if you're a math nerd.

πŸ“Œ Syntax:
πš‚π™΄π™»π™΄π™²πšƒ *
π™΅πšπ™Ύπ™Ό πšπšŠπš‹πš•πšŽ_𝟷
π™²πšπ™Ύπš‚πš‚ 𝙹𝙾𝙸𝙽 πšπšŠπš‹πš•πšŽ_𝟸

Note that there is no need for an ON clause.

CROSS JOIN is useful for getting all combinations
- Matching users with all dates.
- Match product tables with color tables to get product of all colors

πŸ›‘ Be careful though! CROSS JOIN can be very expensive, especially when the tables are huge.

If the user table has 100 records, and date table has 365 records, the result of π˜Ύπ™π™Šπ™Žπ™Ž π™…π™Šπ™„π™‰ is a table of of all users for all the dates (100x365 = 36500 records)

πŸ‘‡ If you're confused, the example below might clarify better. Check it out!

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