Ignore nulls in Postgres

Despite the lack of ignore nulls syntax in postgres, we can mimic the required behavior by defining custom aggregates. Albeit being simple, it has several advantages.

Oracle SQL certificate – is it worth it?

Some time ago I have passed an exam 1Z0-071 Oracle Database SQL and received the certificate. I have stumbled across many problems, majority of them being of organizational nature. Here is a wrap up of how it looks like and what to expect. Note: I am not going to address the content of the exam, particular