Shaun Thomas shows off some functionality:
There’s been a kind of persistent myth regarding Postgres since I first started using it seriously over 20 years ago: “Postgres doesn’t support user variables.” This hasn’t really been true since version 8.0 way back in 2005. Part of this stems from the fact it doesn’t do things the same way as other common database engines.
Why don’t we spend a little time exploring the functionality that time forgot?
Reading through the post, I’m pretty happy with the way MySQL and SQL Server do it, even if SQL Server’s variables are batch-level and can be annoying if you want to maintain variable state across batches. In that case, you’d typically use a user-defined table type or temp table to store the values and re-instate them in the next batch.