ALTER TABLE TBL ADD BLAH_BLAH_BLAH INTEGER;

SET SQL DIALECT 1;

SET NAMES WIN1251;

CREATE DATABASE 'LOCALHOST:C:\DATA\DAMAGE.FDB'
USER 'SYSDBA' PASSWORD 'masterkey'
PAGE_SIZE 16384
DEFAULT CHARACTER SET WIN1251 COLLATION WIN1251;

CREATE SEQUENCE GEN_TBL_ID;

CREATE DOMAIN PK_INT AS
INTEGER
NOT NULL;

CREATE DOMAIN STR_32 AS
VARCHAR(32);

CREATE TABLE TBL (
    TBL_ID   PK_INT NOT NULL,
    UPD_CNT  PK_INT,
    STR_VAL  STR_32,
    COMP     COMPUTED BY ('UPD #<' || CAST(UPD_CNT AS VARCHAR(10)) || '>')
);

ALTER TABLE TBL ADD CONSTRAINT PK_TBL PRIMARY KEY (TBL_ID);
CREATE INDEX TBL_UPD ON TBL (UPD_CNT);

SET TERM ^ ;

CREATE TRIGGER TBL_BI FOR TBL
ACTIVE BEFORE INSERT POSITION 0
AS
BEGIN
  IF (NEW.TBL_ID IS NULL) THEN
    NEW.TBL_ID = GEN_ID(GEN_TBL_ID, 1);
  NEW.UPD_CNT = 0;
  NEW.STR_VAL = 'String Value #<' || CAST(NEW.TBL_ID AS VARCHAR(10)) || '>';
END^

SET TERM ; ^

SET TERM ^ ;

CREATE PROCEDURE UPD_TBL(UPD_ID INTEGER)
RETURNS (RES SMALLINT)
AS
DECLARE VARIABLE UPD_VAL INTEGER;
BEGIN
  SELECT UPD_CNT FROM TBL WHERE TBL_ID = :UPD_ID INTO :UPD_VAL;
  IF (UPD_VAL IS NULL) THEN
    RES = 0;
  ELSE
    BEGIN
      RES = 1;
      UPD_VAL = :UPD_VAL + 1;
      UPDATE TBL SET UPD_CNT = :UPD_VAL WHERE TBL_ID = :UPD_ID;
      WHEN ANY DO RES = -1;
    END
  SUSPEND;
END^

SET TERM ; ^

EXECUTE BLOCK
AS
  DECLARE VARIABLE ID INTEGER;
BEGIN
  ID = 0;
  WHILE (ID < 1000000) DO
    BEGIN
      INSERT INTO TBL(TBL_ID) VALUES (NULL);
      ID = GEN_ID(GEN_TBL_ID, 0);
    END
END;

COMMIT;

SET STATISTICS INDEX PK_TBL;
SET STATISTICS INDEX TBL_UPD;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Label1: TLabel;
    pFIBDatabase1: TpFIBDatabase;
    pFIBTransaction1: TpFIBTransaction;
    pFIBQuery1: TpFIBQuery;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
    Run : boolean;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.FormCreate(Sender: TObject);
begin
  Run := False;
  pFIBDatabase1.Connected := True;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Id : integer;
begin
  if Run then   Exit;
  Run := True;
  while Run do
    begin
      Id := Round(Random * 1000000);
      pFIBTransaction1.StartTransaction;
      pFIBQuery1.Params[0].AsInteger := Id;
      pFIBQuery1.ExecQuery;
      pFIBTransaction1.Commit;
      Label1.Caption := IntToStr(Succ(StrToInt(Label1.Caption)));
      Application.ProcessMessages;
      Sleep(250);
    end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  Run := False;
end;

write
nowait
rec_version
read_committed

SELECT RES FROM UPD_TBL(:ID)