GitHub CodespacesにMySQLをインストール

sudo apt update \
  && sudo apt install -y mysql-server \
  && sudo service mysql start \
  && echo "ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY ''" | sudo mysql \
  && sudo service --status-all \
  && mysql -h127.0.0.1 -uroot

PHPから触るには？

sudo apt install -y php-mysql

もしくは

Laravelの場合

sudo apt update
sudo apt install software-properties-common ca-certificates lsb-release apt-transport-https
LC_ALL=C.UTF-8 sudo add-apt-repository ppa:ondrej/php
sudo apt update
sudo apt install -y php8.2 php8.2-mysql php8.2-mbstring php8.2-xml php8.2-curl
echo APP_URL=https://$CODESPACE_NAME-8000.app.github.dev >> .env
php8.2 artisan serve