自己mac电脑安装mysql，这里记录下，方便后面升级mysql或遇到版本兼容问题作出排查.

#搜索查看可用版本
# tk @ MacBook-Pro in ~/www/l_project on git:test x [16:26:44] C:1
$ brew search mysql
==> Formulae
automysqlbackup          mysql-client             mysql-connector-c++      mysql-utilities          mysql@5.7
mysql                    mysql-cluster            mysql-sandbox            mysql@5.5                mysqltuner
mysql++                  mysql-connector-c        mysql-search-replace     mysql@5.6

==> Casks
mysql-connector-python                   mysql-utilities                          navicat-for-mysql
mysql-shell                              mysqlworkbench                           sqlpro-for-mysql


# tk @ MacBook-Pro in ~/www/l_project on git:test x [16:28:15] 
$ brew install mysql@5.7
Warning: You are using macOS 10.15.
We do not provide support for this pre-release version.
You will encounter build failures with some formulae.
Please create pull requests instead of asking for help on Homebrew's GitHub,
Discourse, Twitter or IRC. You are responsible for resolving any issues you
experience, as you are running this pre-release version.

==> Downloading https://homebrew.bintray.com/bottles/mysql@5.7-5.7.26.mojave.bottle.tar.gz
==> Downloading from https://akamai.bintray.com/81/815ae8aa8c765f57e806ff9197eaa5783b138c493d68333c553b25f441b6af3e?__gda__
######################################################################## 100.0%
==> Pouring mysql@5.7-5.7.26.mojave.bottle.tar.gz
==> /usr/local/Cellar/mysql@5.7/5.7.26/bin/mysqld --initialize-insecure --user=tankun --basedir=/usr/local/Cellar/mysql@5.7
==> Caveats
We've installed your MySQL database without a root password. To secure it run:
    mysql_secure_installation

MySQL is configured to only allow connections from localhost by default

To connect run:
    mysql -uroot

mysql@5.7 is keg-only, which means it was not symlinked into /usr/local,
because this is an alternate version of another formula.

If you need to have mysql@5.7 first in your PATH run:
  echo 'export PATH="/usr/local/opt/mysql@5.7/bin:$PATH"' >> ~/.zshrc

For compilers to find mysql@5.7 you may need to set:
  export LDFLAGS="-L/usr/local/opt/mysql@5.7/lib"
  export CPPFLAGS="-I/usr/local/opt/mysql@5.7/include"


To have launchd start mysql@5.7 now and restart at login:
  brew services start mysql@5.7
Or, if you don't want/need a background service you can just run:
  /usr/local/opt/mysql@5.7/bin/mysql.server start
==> Summary