Today I Learned is an open-source project by Hashrocket that exists to catalogue the sharing & accumulation of knowledge as it happens day-to-day. Posts have a 200-word limit, and posting is open to any Rocketeer as well as selected friends of Hashrocket. We hope you enjoy learning along with us.
- /hashrockettil
- /hashrocket/tilex

Today I Learned

A Hashrocket project Follow on Twitter

Is It Null Or Not Null?

In PostgreSQL, the standard way to check if something is NULL is like so:

select * as wild_pokemons from pokemons where trainer_id is null;

To check if something is not null, you just add not:

select * as captured_pokemons from pokemons where trainer_id is not null;

PostgreSQL also comes with ISNULL and NOTNULL which are non-standard ways of doing the same as above:

select * as wild_pokemons from pokemons where trainer_id isnull;

select * as captured_pokemons from pokemons where trainer_id notnull;

See More #sql TILs

Looking for help? Hashrocket developers believe that data quality is as important as code quality. We enjoy all the challenges of relational databases, from finding the fastest index, to structuring data to fit the needs of an application. We're eager to share our experiences; check out PG Casts, our series of free PostgreSQL screencasts.