CODE EXAMPLE FOR SQL

LoadError: cannot load such file -- mysql2/2.7/mysql2

rm Gemfile.lock
gem uninstall mysql2
gem install mysql2 -v '0.5.2' -- --with-mysql-config=/usr/local/Cellar/mysql@5.7/5.7.25/bin/mysql_config --with-ldflags=-L/usr/local/opt/openssl/lib --with-cppflags=-I/usr/local/opt/openssl/include --platform=ruby
bundle install