How to update multiple tables through a loop?

Question

PHP

In a little more detail, there is a script that updates the number in the Number table + you need to check this number X in another table, that is.
users>number>11-111-111
idnum>inumber>11-111-111
Also another table but Null will be allowed there and it does nothing there
AND change them to another number.
I read about JOIN but did not understand how to update several databases
I ask for help from those who know)