Hello, I offer a small correction to the Postgresql documentation at https://www.postgresql.org/docs/9.1/static/functions-comparison.html as regards not using the operator = with the Null state:
"The null value represents an unknown value" As SQL null is a state, not a value, the reason not to use the operator is that querying the null state returns no value. So, a more accurate sentence might be: "The null state usually represents an unknown value". Thanks, Alex ---------- Forwarded message ---------- From: "Josh Berkus" <j...@agliodbs.com> Date: 12 Oct 2016 6:04 p.m. Subject: Re: SQL Null To: "Alex Lydiate" <alexlydi...@gmail.com> Cc: On 10/12/2016 09:50 AM, Alex Lydiate wrote: > It's not a question, it is a suggestion as that this little piece of > documentation is incorrect, as regards not using the operator = with the > Null state: > > "The null value represents an unknown value, and it is not known whether > two unknown values are equal" > > As SQL null is a state, not a value, the reason not to use the operator > is that querying the null state returns no value. So, a more accurate > sentence might be: > > "The null state usually represents an unknown value, and it is not known > whether two unknown values are equal". That seems fine. Please send this suggested correction to the pgsql-docs@postgresql.org mailing list. -- -- Josh Berkus Red Hat OSAS (any opinions are my own)