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PostgreSQL error code

PostgreSQL error 42P06

42P06 is the SQLSTATE PostgreSQL reports for duplicate schema, in class 42, Syntax Error or Access Rule Violation.

SQLSTATE42P06
Condition nameduplicate_schema
Class42 — Syntax Error or Access Rule Violation

Reproduce it, then fix it

The schema is already there. IF NOT EXISTS makes a setup script safe to run twice. Run the broken query to see the error, then switch to the fixed one. Edit either freely; every run is rolled back.

CREATE SCHEMA demo;
CREATE SCHEMA IF NOT EXISTS demo;

Source: PostgreSQL documentation, Appendix A