Access the database with minimal privilege
If your Go web application only needs to read data and doesn't need to write
information, create a database user whose permissions are
Always adjust the database user according to your web applications needs.
Use a strong password
When creating your database access, choose a strong password. You can use password managers to generate a strong password or use online web applications that do the same for you - Strong Password Generator.
Remove default admin passwords
Most DBS have default accounts and most of them have no passwords on their highest privilege user.
MariaDB, MongoDB - root/no password
Which means that if there is no password, the attacker could gain access to everything.
Also, don't forget to remove your credentials and/or private key(s) if you're going to post your code on a publicly accessible repository in Github.