Create PostgreSQL ROLE (user) If It Doesn't Exist
Answer : Simplify in a similar fashion to what you had in mind: DO $do$ BEGIN IF NOT EXISTS ( SELECT FROM pg_catalog.pg_roles -- SELECT list can be empty for this WHERE rolname = 'my_user') THEN CREATE ROLE my_user LOGIN PASSWORD 'my_password'; END IF; END $do$; (Building on @a_horse_with_no_name's answer and improved with @Gregory's comment.) Unlike, for instance, with CREATE TABLE there is no IF NOT EXISTS clause for CREATE ROLE (up to at least pg 12). And you cannot execute dynamic DDL statements in plain SQL. Your request to "avoid PL/pgSQL" is impossible except by using another PL. The DO statement uses plpgsql as default procedural language. The syntax allows to omit the explicit declaration: DO [ LANGUAGE lang_name ] code ... lang_name The name of the procedural language the code is written in. If omitted, the default is plpgsql . The accepted answer suffers from a race condition if two such scripts...