Postgres database create if not exists

Question

Is there an analog to CREATE TABLE IF NOT EXISTS for creating databases?

Background: I am writing a script to automatically set up the schema in PostgreSQL on an unknown system. I am not sure if the database (or even part of the schema) was already deployed, so I want to structure my code to not fail (or ideally even show errors) if some of the structure already exists. I want to differentiate the errors that prevent me from creating a database (so abort future schema changes since they will not work) from this error.

Solution

No but you could query the pg_catalog.pg_database table to see if it exists.

Comments

[ahanin]

You need to do this in function then, and this wouldn't work in 9.3, because Postgres doesn't allow to create/drop databases from inside function or multi-command string.

[Eelke]

But you could write an external script in php, python, perl or whatever you favour.

[Enwired]

Wouldn't it be simpler to just use DROP TABLE IF EXISTS "foo"; CREATE TABLE "foo";

[Steve Midgley]

@Enwired - what if you don't want to drop the existing table if it exists? You might want to create it if it doesn't exist, but leave it alone if it does.

[Enwired]

If that is what you want, then the commands I specified wouldn't be useful for you. The original question was actually about creating a database, not a table, so my comment was accidentally off-topic anyway! Sorry.