While this question is specific to Apple Silicon and mysql 5.7, and I will address that in this answer, I would like to start by adding some general notes to save others time:
Homebrew supports mysql 5.7 for both intel and apple silicon.
https://formulae.brew.sh/formula/mysql@5.7
Homebrew supports mysql 5.6 for the intel chip, but not apple silicon:
https://formulae.brew.sh/formula/mysql@5.6
If you need 5.6 on apple silicon, it's probably a good idea to just settle with 5.7 since production will need to be upgraded eventually and the differences aren't that big.
In my situation I originally did brew install mysql and it gave me the latest mysql (currently 8.0). When I tried going back over it and doing brew install mysql@5.6, of course this didn't work due to not being supported on the m1 max (apple silicon). I ran into issues then trying to get brew install mysql@5.7 working. I followed some guides mentioning various suggestions. After playing with it for a while, it seems that running two versions of mysql at once will corrupt your mysql files and make it hard to work with and confuse homebrew.
I came across these guides:
brew install mysql on macOS
https://coderwall.com/p/os6woq/uninstall-all-those-broken-versions-of-mysql-and-re-install-it-with-brew-on-mac-mavericks
https://www.codegrepper.com/code-examples/shell/brew+uninstall+mysql
Before reading further, note that in my situation, I had a zip available for my whole local mysql database needs and could risk destroying what I have.
Warning! Reading further and executing these commands carelessly may delete your mysql storage. Make sure you have a backup.
brew remove mysql is a good command that got rid of my latest install.
I also needed brew remove mysql@5.7 even though this is the version I'm trying to install, but they were stepping on each other's foot...
brew cleanup is nice, I noticed it freed up some lock files.
I don't recall having any luck with:
launchctl unload -w ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist
but you can try it.
rm ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist has worked for me.
But note there will also be another file in there for your 5.7 setup.
I'd recommend:
cd ~/Library/LaunchAgents/ then look around to see if you have any mysql* in there. Then if you do, such as homebrew.mxcl.mysql@5.7.plist, then remove it.
These are some that worked for me:
sudo rm -rf /usr/local/var/mysql
rm /usr/local/etc/my.cnf
rm /usr/local/etc/my.cnf.default
Also:
cd opt/homebrew/var
Then if you notice a mysql directory in there, remove it.
It's possible you might have docker or something else similar also running mysql or mysqld.
ps -ax | grep "[m]ysql"
(Note the brackets and quotes in the above is to prevent the grep from showing up in the process list and matching itself unlike the lazier version: ps -ax | grep mysql which will give the impression there's an extra mysql process running)
Once you're ready, please run:
brew services list
double-check you don't have mysql in there.
Then double check you don't have any mysql process running:
ps -ax | grep "[m]ysql"
This can happen for example if you enter mysqld for example....
You might need to do brew services stop mysql or brew services stop mysql@5.7 or similar and repeat steps if you see anything on the service list or process list.
Finally, you should be ready for a fresh install.
The fresh installation process should be rather straight forward:
brew install mysql@5.7
brew link --force mysql@5.7
brew services start mysql@5.7
Then run brew services list to make sure your installation worked correctly.
If you see it's green and "started", your installation was successful!
You should also run:
mysql_secure_installation
Then choose a password for root and go through the list of questions like validation, etc.
Once you're installed, you might also run into mysql mode issues.
cd /opt/homebrew/etc and you should find a my.cnf file.
Edit it using either vim or nano.
You should see something like:
# Default Homebrew MySQL server config
[mysqld]
# Only allow connections from localhost
bind-address = 127.0.0.1
Edit it and set the mysql mode. For example, I don't want the no_zero_in_date mode, so I use:
# Default Homebrew MySQL server config
[mysqld]
# Only allow connections from localhost
bind-address = 127.0.0.1
sql-mode="ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
Then restart mysql like so:
brew services restart mysql@5.7
Then double check you still have a green status "started":
brew services list
If you do, then you should have the no_zero_in_date mode disabled.
You can test it with a query:
SELECT @@sql_mode;
You should now have mysql 5.7 running on Apple Silicon and have the sql_mode set.
If you run into more troubleshooting, do your best to get into a known state such as uninstalled, doing a fresh install, or already installed with some version, etc.
