IsCardinalityViolation asserts the error code class is Class 21 — Cardinality Violation.

IsCaseNotFound asserts the error code class is Class 20 — Case Not Found.

IsConfigurationFileError asserts the error code class is Class F0 — Configuration File Error.

IsConnectionException asserts the error code class is Class 08 — Connection Exception.

IsDataException asserts the error code class is Class 22 — Data Exception.

IsDependentPrivilegeDescriptorsStillExist asserts the error code class is Class 2B — Dependent Privilege Descriptors Still Exist.

IsDiagnosticsException asserts the error code class is Class 0Z — Diagnostics Exception.

IsExternalRoutineException asserts the error code class is Class 38 — External Routine Exception.

IsExternalRoutineInvocationException asserts the error code class is Class 39 — External Routine Invocation Exception.

IsFeatureNotSupported asserts the error code class is Class 0A — Feature Not Supported.

IsForeignDataWrapperError asserts the error code class is Class HV — Foreign Data Wrapper Error (SQL/MED).

IsInsufficientResources asserts the error code class is Class 53 — Insufficient Resources.

IsIntegrityConstraintViolation asserts the error code class is Class 23 — Integrity Constraint Violation.

IsInternalError asserts the error code class is Class XX — Internal Error.

IsInvalidAuthorizationSpecification asserts the error code class is Class 28 — Invalid Authorization Specification.

IsInvalidCatalogName asserts the error code class is Class 3D — Invalid Catalog Name.

IsInvalidCursorName asserts the error code class is Class 34 — Invalid Cursor Name.

IsInvalidCursorState asserts the error code class is Class 24 — Invalid Cursor State.

IsInvalidGrantor asserts the error code class is Class 0L — Invalid Grantor.

IsInvalidRoleSpecification asserts the error code class is Class 0P — Invalid Role Specification.

IsInvalidSchemaName asserts the error code class is Class 3F — Invalid Schema Name.

IsInvalidSQLStatementName asserts the error code class is Class 26 — Invalid SQL Statement Name.

IsInvalidTransactionInitiation asserts the error code class is Class 0B — Invalid Transaction Initiation.

IsInvalidTransactionState asserts the error code class is Class 25 — Invalid Transaction State.

IsInvalidTransactionTermination asserts the error code class is Class 2D — Invalid Transaction Termination.

IsLocatorException asserts the error code class is Class 0F — Locator Exception.

IsNoData asserts the error code class is Class 02 — No Data (this is also a warning class per the SQL standard).

IsObjectNotInPrerequisiteState asserts the error code class is Class 55 — Object Not In Prerequisite State.

IsOperatorIntervention asserts the error code class is Class 57 — Operator Intervention.

IsPLpgSQLError asserts the error code class is Class P0 — PL/pgSQL Error.

IsProgramLimitExceeded asserts the error code class is Class 54 — Program Limit Exceeded.

IsSavepointException asserts the error code class is Class 3B — Savepoint Exception.

IsSnapshotFailure asserts the error code class is Class 72 — Snapshot Failure.

IsSQLRoutineException asserts the error code class is Class 2F — SQL Routine Exception.

IsSQLStatementNotYetComplete asserts the error code class is Class 03 — SQL Statement Not Yet Complete.

IsSuccessfulCompletion asserts the error code class is Class 00 — Successful Completion.

IsSyntaxErrororAccessRuleViolation asserts the error code class is Class 42 — Syntax Error or Access Rule Violation.

IsSystemError asserts the error code class is Class 58 — System Error (errors external to PostgreSQL itself).

IsTransactionRollback asserts the error code class is Class 40 — Transaction Rollback.

IsTriggeredActionException asserts the error code class is Class 09 — Triggered Action Exception.

IsTriggeredDataChangeViolation asserts the error code class is Class 27 — Triggered Data Change Violation.

IsWarning asserts the error code class is Class 01 — Warning.

IsWithCheckOptionViolation asserts the error code class is Class 44 — WITH CHECK OPTION Violation.

Class 21 — Cardinality Violation.

Class 20 — Case Not Found.

Class F0 — Configuration File Error.

Class 08 — Connection Exception.

Class 22 — Data Exception.

Class 2B — Dependent Privilege Descriptors Still Exist.

Class 0Z — Diagnostics Exception.

Class 38 — External Routine Exception.

Class 39 — External Routine Invocation Exception.

Class HV — Foreign Data Wrapper Error (SQL/MED).

Class 0A — Feature Not Supported.

Class 53 — Insufficient Resources.

Class 23 — Integrity Constraint Violation.

Class XX — Internal Error.

Class 28 — Invalid Authorization Specification.

Class 3D — Invalid Catalog Name.

Class 34 — Invalid Cursor Name.

Class 24 — Invalid Cursor State.

Class 0L — Invalid Grantor.

Class 0P — Invalid Role Specification.

Class 3F — Invalid Schema Name.

Class 26 — Invalid SQL Statement Name.

Class 0B — Invalid Transaction Initiation.

Class 25 — Invalid Transaction State.

Class 2D — Invalid Transaction Termination.

Class 0F — Locator Exception.

Class 02 — No Data (this is also a warning class per the SQL standard).

Class 55 — Object Not In Prerequisite State.

Class 57 — Operator Intervention.

Class P0 — PL/pgSQL Error.

Class 54 — Program Limit Exceeded.

Class 3B — Savepoint Exception.

Class 72 — Snapshot Failure.

Class 2F — SQL Routine Exception.

Class 03 — SQL Statement Not Yet Complete.

Class 00 — Successful Completion.

Class 42 — Syntax Error or Access Rule Violation.

Class 58 — System Error (errors external to PostgreSQL itself).

Class 40 — Transaction Rollback.

Class 09 — Triggered Action Exception.

Class 27 — Triggered Data Change Violation.

Class 01 — Warning.

Class 44 — WITH CHECK OPTION Violation.

ErrSampleCustomError example custom error.

ErrUsernameAlreadyExist when user register with registered username.

ErrWrongUsernameOrPassword when user try to login with wrong username or password.