Common codes

A curated list of SQLSTATE values useful during incident triage.

This is an editorial entry point for frequent diagnosis paths. It is not a measured ranking of production frequency; each row states the practical question the entry helps answer and preserves its review state.

Code	Condition	Why start here
`23505`	`unique_violation`	Duplicate keys, constraints, and idempotent writes.
`23503`	`foreign_key_violation`	Foreign-key repair and dependency order.
`23502`	`not_null_violation`	Missing required values and input validation.
`23514`	`check_violation`	CHECK constraints and invariant failures.
`23P01`	`exclusion_violation`	Exclusion constraints and range conflicts.
`40P01`	`deadlock_detected`	Deadlock diagnosis, rollback, and lock ordering.
`40001`	`serialization_failure`	Serializable retry and fresh transaction snapshots.
`25P02`	`in_failed_sql_transaction`	The failed transaction state that follows an error.
`42P01`	`undefined_table`	Missing relations and search-path diagnosis.
`42601`	`syntax_error`	Syntax errors before a statement can execute.
`42501`	`insufficient_privilege`	Privilege checks and authorization failures.
`28P01`	`invalid_password`	Password authentication and connection setup.
`57014`	`query_canceled`	Cancellation, statement_timeout, and safe follow-up.
`53300`	`too_many_connections`	Connection limits and admission failures.
`2202E`	`array_subscript_error`	Array dimensions, concatenation, and type rules.
`01000`	`warning`	Warning dispatch and non-error diagnostics.
`P0001`	`raise_exception`	Application-defined PL/pgSQL exceptions.
`XX000`	`internal_error`	Internal-error safety boundaries and escalation.