When logging in, how do you get that autoincremented ID column? Some more complex variant of "SELECT *.id WHERE username = $1". So functionally, yes the usernam

When logging in, how do you get that autoincremented ID column? Some more complex variant of "SELECT *.id WHERE username = $1". So functionally, yes the username is the root identifier that pulls the very first record that then allows other joins to occur. But you are right, the username column is not literally the key being joined on. There is also the security issue that by having the login name also be the publicly displayed name lowers the bar for attempting to make a targeted attack on the site, as well as other sites where the attacker suspects the victim may be using the similar login name. This can particularly be true in cases of harassment across platforms, which while is not a computer science security issue, it is a personal psychological security issue.