452 Функции для работы с генераторами (последовательностями) .............................. 453 GEN_ID .................................................................................................. данных INTEGER. Примеры: Пример 2.1. Использование типа BIGINT CREATE TABLE WHOLELOTTARECORDS ( ID BIGINT NOT NULL PRIMARY KEY, DESCRIPTION VARCHAR(32) ); Шестнадцатеричный формат для целых чисел Значение TRUE больше чем FALSE. Примеры: Пример 2.5. Использование типа BOOLEAN CREATE TABLE TBOOL (ID INT, BVAL BOOLEAN); COMMIT; INSERT INTO TBOOL VALUES (1, TRUE); INSERT INTO TBOOL VALUES (2, 2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 472 8.8.1. GEN_ID(). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ◦ Although generator values are stored as 64-bit integers, a Dialect 1 client request, SELECT GEN_ID (MyGen, 1), for example, will return the generator value truncated to 32 bits. • Dialect 2 is available entitled Common Language Elements. Examples Using Integer Types CREATE TABLE WHOLELOTTARECORDS ( ID BIGINT NOT NULL PRIMARY KEY, DESCRIPTION VARCHAR(32) ); INSERT INTO MYBIGINTS VALUES ( -236453287458723

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359 8.8.1. GEN_ID(). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ◦ Although generator values are stored as 64-bit integers, a Dialect 1 client request, SELECT GEN_ID (MyGen, 1), for example, will return the generator value truncated to 32 bits. • Dialect 2 is available entitled Common Language Elements. Examples Using Integer Types CREATE TABLE WHOLELOTTARECORDS ( ID BIGINT NOT NULL PRIMARY KEY, DESCRIPTION VARCHAR(32) ); INSERT INTO MYBIGINTS VALUES ( -236453287458723

создания уникальных идентификаторов строк. . . . . . . . . 13 4.1. Зачем вообще нужны идентификаторы (ID)? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.2. Один для которые есть в других СУБД; • ищите примеры того, как использовать генераторы для идентификаторов (ID) или для других задач; • хотите узнать, что в СУБД Firebird является аналогом понятия “sequence” CHAR(31) • RDB$GENERATOR_ID SMALLINT • RDB$SYSTEM_FLAG SMALLINT И для СУБД Firebird 2.0 и более старших версий: • RDB$DESCRIPTION BLOB subtype TEXT Обратите внимание, что GENERATOR_ID является идентификатором

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 8.8.1. GEN_ID(). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64-Bit-Ganzzahlen gespeichert werden, gibt eine Dialekt-1- Client-Anfrage, beispielsweise SELECT GEN_ID (MyGen, 1) den Generatorwert auf 32 Bit gekürzt zurück. • Dialekt 2 ist nur über die Firebird-Client-Verbindung Sprachelemente genauer beschrieben. Beispiele mit Integer-Typen CREATE TABLE WHOLELOTTARECORDS ( ID BIGINT NOT NULL PRIMARY KEY, DESCRIPTION VARCHAR(32) ); INSERT INTO MYBIGINTS VALUES ( -236453287458723

COS() COSH() COT() DATEADD() DATEDIFF() DECODE() EXP() EXTRACT() MILLISECOND WEEK FLOOR() GEN_ID() GEN_UUID() HASH() IIF() LEFT() LN() LOG() LOG10() LOWER() LPAD() MAXVALUE() MINVALUE() MOD() NULLIF() CSTRING, DATABASE, DESC, DESCENDING, DESCRIPTOR, DO, DOMAIN, ENTRY_POINT, EXCEPTION, EXIT, FILE, GEN_ID, GENERATOR, IF, INACTIVE, INPUT_TYPE, ISOLATION, KEY, LENGTH, LEVEL, MANUAL, MODULE_NAME, NAMES CONTAINING CSTRING DATABASE DESC DESCENDING DESCRIPTOR DO DOMAIN ENTRY_POINT EXCEPTION EXIT FILE FREE_IT GEN_ID GENERATOR IF INACTIVE INPUT_TYPE ISOLATION KEY LENGTH LEVEL MANUAL MODULE_NAME NAMES OPTION OUTPUT_TYPE

USHORT hdr_sequence; USHORT hdr_flags; SLONG hdr_creation_date[2]; SLONG hdr_attachment_id; SLONG hdr_shadow_count; SSHORT hdr_implementation; USHORT hdr_ods_minor; USHORT h otherwise. hdr_oldest_transaction Four bytes, signed. Bytes 0x1c - 0x1f on the page. The transaction id of the oldest active (ie, uncommitted — but may be in limbo or rolled back) transaction against this set to zero. hdr_oldest_active Four bytes, signed. Bytes 0x20 - 0x23 on the page. The transaction id of the oldest active transaction against this database, when any active transaction started. This

CHAR(31) • RDB$GENERATOR_ID SMALLINT Chapter 2. Generator Basics 3 • RDB$SYSTEM_FLAG SMALLINT And, as from Firebird 2.0: • RDB$DESCRIPTION BLOB subtype TEXT Note that the GENERATOR_ID is — as the name says Also, don’t let your applications store the ID for later use as a handle to the generator. Apart from this making no sense (the name is the handle), the ID may be changed after a backup-restore cycle RDB$GENERATORS table, here with a single self-defined generator: RDB$GENERATOR_NAME RDB$GENERATOR_ID RDB$SYSTEM_FLAG RDB$SECURITY_CLASS 1 1 SQL$DEFAULT 2 1 RDB$PROCEDURES 3 1 RDB$EXCEPTIONS 4 1 RDB$CONSTRAINT_NAME

RDB$GENERATOR_NAME CHAR(31) • RDB$GENERATOR_ID SMALLINT • RDB$SYSTEM_FLAG SMALLINT Und, von Firebird 2.0 an: • RDB$DESCRIPTION BLOB subtype TEXT Man beachte, dass die GENERATOR_ID – wie der Name schon sagt – ein nicht diese ID in seinen Anwendungen benutzen, um später auf Generatoren zuzugreifen. Abgesehen davon, dass dies wenig Sinn macht (der Name identifiziert den Generator), kann sich die GENERATOR_ID nach einem RDB$GENERATORS-Tabelle, hier mit einem einzigen selbstdefinierten Generator: RDB$GENERATOR_NAME RDB$GENERATOR_ID RDB$SYSTEM_FLAG RDB$SECURITY_CLASS 1 1 SQL$DEFAULT 2 1 RDB$PROCEDURES 3 1 RDB$EXCEPTIONS 4 1 RDB$CONSTRAINT_NAME

de documentação bruta sobre um assunto que você conheça muito bem. • Fale sobre suas idéias - ou sua busca por idéias - na lista de discussão firebird-docs. A freqüência de postagem pode ser muito baixa e respondida. Guia de escrita 6 Preparando-se para escrever: faça um resumo! É sempre uma boa idéia pazer um resumo antes de escrever o texto propriamentedito. Preparar um resumo ajuda você a "ficar sobre XML. Agora você deve ter uma idéia geral de como um texto em XML se aparenta, o que são tags e elementos, e para quê eles existem. E como eu disse antes, a idéia é supersimplificada mas é suficiente