now to start postgresql code example

Example 1: how-can-i-start-postgresql-server-on-mac-os-x

If you want to manually start and stop PostgreSQL (installed via Homebrew), the easiest way is:

brew services start postgresql

and

brew services stop postgresql

If you have a specific version, make sure to suffix the version. For example:

brew services start postgresql@10

Example 2: start postgres server

pg_ctl -D /usr/local/var/postgres start