sunaoka
diff --git a/‎src/PostgresError.php
+85 b/‎src/PostgresError.php
+85
@@ -4,7 +4,10 @@
 
 class PostgresError
 {
+    // Class 00 - Successful Completion
     const SUCCESSFUL_COMPLETION = '00000';
+
+    // Class 01 - Warning
     const WARNING = '01000';
     const DYNAMIC_RESULT_SETS_RETURNED = '0100C';
     const IMPLICIT_ZERO_BIT_PADDING = '01008';
@@ -13,28 +16,54 @@ class PostgresError
     const PRIVILEGE_NOT_REVOKED = '01006';
     const STRING_DATA_RIGHT_TRUNCATION = '01004';
     const DEPRECATED_FEATURE = '01P01';
+
+    // Class 02 - No Data (this is also a warning class per the SQL standard)
     const NO_DATA = '02000';
     const NO_ADDITIONAL_DYNAMIC_RESULT_SETS_RETURNED = '02001';
+
+    // Class 03 - SQL Statement Not Yet Complete
     const SQL_STATEMENT_NOT_YET_COMPLETE = '03000';
+
+    // Class 08 - Connection Exception
     const CONNECTION_EXCEPTION = '08000';
     const CONNECTION_DOES_NOT_EXIST = '08003';
     const CONNECTION_FAILURE = '08006';
     const SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION = '08001';
     const SQLSERVER_REJECTED_ESTABLISHMENT_OF_SQLCONNECTION = '08004';
     const TRANSACTION_RESOLUTION_UNKNOWN = '08007';
     const PROTOCOL_VIOLATION = '08P01';
+
+    // Class 09 - Triggered Action Exception
     const TRIGGERED_ACTION_EXCEPTION = '09000';
+
+    // Class 0A - Feature Not Supported
     const FEATURE_NOT_SUPPORTED = '0A000';
+
+    // Class 0B - Invalid Transaction Initiation
     const INVALID_TRANSACTION_INITIATION = '0B000';
 
+    // Class 0F - Locator Exception
     const LOCATOR_EXCEPTION = '0F000';
     const INVALID_LOCATOR_SPECIFICATION = '0F001';
+
+    // Class 0L - Invalid Grantor
     const INVALID_GRANTOR = '0L000';
     const INVALID_GRANT_OPERATION = '0LP01';
+
+    // Class 0P - Invalid Role Specification
     const INVALID_ROLE_SPECIFICATION = '0P000';
+
+    // Class 0Z - Diagnostics Exception
     const DIAGNOSTICS_EXCEPTION = '0Z000';
     const STACKED_DIAGNOSTICS_ACCESSED_WITHOUT_ACTIVE_HANDLER = '0Z002';
+
+    // Class 20 - Case Not Found
     const CASE_NOT_FOUND = '20000';
+
+    // Class 21 - Cardinality Violation
     const CARDINALITY_VIOLATION = '21000';
+
+    // Class 22 - Data Exception
     const DATA_EXCEPTION = '22000';
     const ARRAY_SUBSCRIPT_ERROR = '2202E';
     const CHARACTER_NOT_IN_REPERTOIRE = '22021';
@@ -102,14 +131,20 @@ class PostgresError
     const TOO_MANY_JSON_ARRAY_ELEMENTS = '2203D';
     const TOO_MANY_JSON_OBJECT_MEMBERS = '2203E';
     const SQL_JSON_SCALAR_REQUIRED = '2203F';
+
+    // Class 23 - Integrity Constraint Violation
     const INTEGRITY_CONSTRAINT_VIOLATION = '23000';
     const RESTRICT_VIOLATION = '23001';
     const NOT_NULL_VIOLATION = '23502';
     const FOREIGN_KEY_VIOLATION = '23503';
     const UNIQUE_VIOLATION = '23505';
     const CHECK_VIOLATION = '23514';
     const EXCLUSION_VIOLATION = '23P01';
+
+    // Class 24 - Invalid Cursor State
     const INVALID_CURSOR_STATE = '24000';
+
+    // Class 25 - Invalid Transaction State
     const INVALID_TRANSACTION_STATE = '25000';
     const ACTIVE_SQL_TRANSACTION = '25001';
     const BRANCH_TRANSACTION_ALREADY_ACTIVE = '25002';
@@ -122,39 +157,67 @@ class PostgresError
     const NO_ACTIVE_SQL_TRANSACTION = '25P01';
     const IN_FAILED_SQL_TRANSACTION = '25P02';
     const IDLE_IN_TRANSACTION_SESSION_TIMEOUT = '25P03';
+
+    // Class 26 - Invalid SQL Statement Name
     const INVALID_SQL_STATEMENT_NAME = '26000';
+
+    // Class 27 - Triggered Data Change Violation
     const TRIGGERED_DATA_CHANGE_VIOLATION = '27000';
+
+    // Class 28 - Invalid Authorization Specification
     const INVALID_AUTHORIZATION_SPECIFICATION = '28000';
     const INVALID_PASSWORD = '28P01';
+
+    // Class 2B - Dependent Privilege Descriptors Still Exist
     const DEPENDENT_PRIVILEGE_DESCRIPTORS_STILL_EXIST = '2B000';
     const DEPENDENT_OBJECTS_STILL_EXIST = '2BP01';
+
+    // Class 2D - Invalid Transaction Termination
     const INVALID_TRANSACTION_TERMINATION = '2D000';
+
+    // Class 2F - SQL Routine Exception
     const SQL_ROUTINE_EXCEPTION = '2F000';
     const FUNCTION_EXECUTED_NO_RETURN_STATEMENT = '2F005';
     const MODIFYING_SQL_DATA_NOT_PERMITTED = '2F002';
     const PROHIBITED_SQL_STATEMENT_ATTEMPTED = '2F003';
     const READING_SQL_DATA_NOT_PERMITTED = '2F004';
+
+    // Class 34 - Invalid Cursor Name
     const INVALID_CURSOR_NAME = '34000';
+
+    // Class 38 - External Routine Exception
     const EXTERNAL_ROUTINE_EXCEPTION = '38000';
     const CONTAINING_SQL_NOT_PERMITTED = '38001';
     const MODIFYING_SQL_DATA_NOT_PERMITTED_EXCEPTION = '38002';
     const PROHIBITED_SQL_STATEMENT_ATTEMPTED_EXCEPTION = '38003';
     const READING_SQL_DATA_NOT_PERMITTED_EXCEPTION = '38004';
+
+    // Class 39 - External Routine Invocation Exception
     const EXTERNAL_ROUTINE_INVOCATION_EXCEPTION = '39000';
     const INVALID_SQLSTATE_RETURNED = '39001';
     const NULL_VALUE_NOT_ALLOWED_EXCEPTION = '39004';
     const TRIGGER_PROTOCOL_VIOLATED = '39P01';
     const SRF_PROTOCOL_VIOLATED = '39P02';
     const EVENT_TRIGGER_PROTOCOL_VIOLATED = '39P03';
+
+    // Class 3B - Savepoint Exception
     const SAVEPOINT_EXCEPTION = '3B000';
     const INVALID_SAVEPOINT_SPECIFICATION = '3B001';
+
+    // Class 3D - Invalid Catalog Name
     const INVALID_CATALOG_NAME = '3D000';
+
+    // Class 3F - Invalid Schema Name
     const INVALID_SCHEMA_NAME = '3F000';
+
+    // Class 40 - Transaction Rollback
     const TRANSACTION_ROLLBACK = '40000';
     const TRANSACTION_INTEGRITY_CONSTRAINT_VIOLATION = '40002';
     const SERIALIZATION_FAILURE = '40001';
     const STATEMENT_COMPLETION_UNKNOWN = '40003';
     const DEADLOCK_DETECTED = '40P01';
+
+    // Class 42 - Syntax Error or Access Rule Violation
     const SYNTAX_ERROR_OR_ACCESS_RULE_VIOLATION = '42000';
     const SYNTAX_ERROR = '42601';
     const INSUFFICIENT_PRIVILEGE = '42501';
@@ -199,35 +262,53 @@ class PostgresError
     const INVALID_SCHEMA_DEFINITION = '42P15';
     const INVALID_TABLE_DEFINITION = '42P16';
     const INVALID_OBJECT_DEFINITION = '42P17';
+
+    // Class 44 - WITH CHECK OPTION Violation
     const WITH_CHECK_OPTION_VIOLATION = '44000';
+
+    // Class 53 - Insufficient Resources
     const INSUFFICIENT_RESOURCES = '53000';
     const DISK_FULL = '53100';
     const OUT_OF_MEMORY = '53200';
     const TOO_MANY_CONNECTIONS = '53300';
     const CONFIGURATION_LIMIT_EXCEEDED = '53400';
+
+    // Class 54 - Program Limit Exceeded
     const PROGRAM_LIMIT_EXCEEDED = '54000';
     const STATEMENT_TOO_COMPLEX = '54001';
     const TOO_MANY_COLUMNS = '54011';
     const TOO_MANY_ARGUMENTS = '54023';
+
+    // Class 55 - Object Not In Prerequisite State
     const OBJECT_NOT_IN_PREREQUISITE_STATE = '55000';
     const OBJECT_IN_USE = '55006';
     const CANT_CHANGE_RUNTIME_PARAM = '55P02';
     const LOCK_NOT_AVAILABLE = '55P03';
     const UNSAFE_NEW_ENUM_VALUE_USAGE = '55P04';
+
+    // Class 57 - Operator Intervention
     const OPERATOR_INTERVENTION = '57000';
     const QUERY_CANCELED = '57014';
     const ADMIN_SHUTDOWN = '57P01';
     const CRASH_SHUTDOWN = '57P02';
     const CANNOT_CONNECT_NOW = '57P03';
     const DATABASE_DROPPED = '57P04';
     const IDLE_SESSION_TIMEOUT = '57P05';
+
+    // Class 58 - System Error (errors external to PostgreSQL itself)
     const SYSTEM_ERROR = '58000';
     const IO_ERROR = '58030';
     const UNDEFINED_FILE = '58P01';
     const DUPLICATE_FILE = '58P02';
+
+    // Class 72 - Snapshot Failure
     const SNAPSHOT_TOO_OLD = '72000';
+
+    // Class F0 - Configuration File Error
     const CONFIG_FILE_ERROR = 'F0000';
     const LOCK_FILE_EXISTS = 'F0001';
+
+    // Class HV - Foreign Data Wrapper Error (SQL/MED)
     const FDW_ERROR = 'HV000';
     const FDW_COLUMN_NAME_NOT_FOUND = 'HV005';
     const FDW_DYNAMIC_PARAMETER_VALUE_NEEDED = 'HV002';
@@ -255,11 +336,15 @@ class PostgresError
     const FDW_UNABLE_TO_CREATE_EXECUTION = 'HV00L';
     const FDW_UNABLE_TO_CREATE_REPLY = 'HV00M';
     const FDW_UNABLE_TO_ESTABLISH_CONNECTION = 'HV00N';
+
+    // Class P0 - PL/pgSQL Error
     const PLPGSQL_ERROR = 'P0000';
     const RAISE_EXCEPTION = 'P0001';
     const NO_DATA_FOUND = 'P0002';
     const TOO_MANY_ROWS = 'P0003';
     const ASSERT_FAILURE = 'P0004';
+
+    // Class XX - Internal Error
     const INTERNAL_ERROR = 'XX000';
     const DATA_CORRUPTED = 'XX001';
     const INDEX_CORRUPTED = 'XX002';