CREATE TABLE Doc_Lock (
  Table_Name char( 128 ) NOT NULL,
  Doc_id char( 128 ) NOT NULL,
  User_Name char( 128 ) NOT NULL,
  PRIMARY KEY (Table_Name, Doc_id)
);
CREATE INDEX User_Name ON Doc_Lock (User_Name);

CREATE PROCEDURE sp_Doc_Lock (
  IN @Table_Name char( 128 ),
  IN @Doc_id char( 128 ),
  IN @Lock_Type char( 1 ),
  IN @User_Name char( 128 ) DEFAULT NULL
)
BEGIN
  DECLARE @Cur_User_Name char( 128 );

  IF IsNull(@Lock_Type, '') NOT IN ('+', '-')
  THEN
    RAISERROR  20000  'Указан неизвестный режим блокировки "' || @Lock_Type || '"';
    RETURN;
  END IF;

  SET @User_Name = IsNull(@User_Name, CURRENT USER);

  IF @Lock_Type = '+'
  THEN
    SELECT User_Name
    INTO @Cur_User_Name
    FROM Doc_Lock
    WHERE Table_Name = @Table_Name AND Doc_id = @Doc_id;

    IF @Cur_User_Name IS NOT NULL AND @Cur_User_Name <> @User_Name
    THEN
      RAISERROR  20000  'Документ уже заблокирован пользователем "' || @Cur_User_Name || '"';
      RETURN;
    END IF;

    IF @Cur_User_Name IS NULL
    THEN
      INSERT INTO Doc_Lock (Table_Name, Doc_id, User_Name)
      VALUES (@Table_Name, @Doc_id, @User_Name);
    END IF;

    COMMIT;
  ELSE
    DELETE FROM Doc_Lock
    WHERE Table_Name = @Table_Name AND Doc_id = @Doc_id AND User_Name = @User_Name;

    IF @@ROWCOUNT =  0 
    THEN
      ROLLBACK;
      RAISERROR  20000  'Блокировка документа отсутствует';
      RETURN;
    END IF;

    COMMIT;
  END IF;
END;

...
CALL sp_Doc_Lock (@Table_Name = 'Table1', @Doc_id =  1 , @Lock_Type = '+');
...
CALL sp_Doc_Lock (@Table_Name = 'Table1', @Doc_id =  1 , @Lock_Type = '-');
...

CREATE EVENT "Doc_Lock_Proccess_Disconnect" TYPE "Disconnect"
HANDLER
BEGIN
  DECLARE @User_Name char( 128 );
  SET @User_Name = EVENT_PARAMETER('User');

  DELETE FROM Doc_Lock
  WHERE User_Name = @User_Name;

  COMMIT;
END;

CREATE TABLE "DBA"."Doc_Lock" (
  "Table_Name" char( 128 ) NOT NULL,
  "Doc_id" char( 128 ) NOT NULL,
  "User_Name" char( 128 ) NOT NULL DEFAULT current user,
  "Connect_id" unsigned int NOT NULL,
  "Lock_Date" timestamp NOT NULL DEFAULT current timestamp,
  PRIMARY KEY ( "Table_Name", "Doc_id" )
);
COMMENT ON TABLE "DBA"."Doc_Lock" IS 'Логические блокировки';
COMMENT ON COLUMN "DBA"."Doc_Lock"."Table_Name" IS 'Имя таблицы';
COMMENT ON COLUMN "DBA"."Doc_Lock"."Doc_id" IS 'Код документа';
COMMENT ON COLUMN "DBA"."Doc_Lock"."User_Name" IS 'Логин пользователя';
COMMENT ON COLUMN "DBA"."Doc_Lock"."Connect_id" IS 'Код сессии';
COMMENT ON COLUMN "DBA"."Doc_Lock"."Lock_Date" IS 'Время начала блокировки';

CREATE PROCEDURE "DBA"."sp_Doc_Lock" (
  IN @Table_Name char( 128 ),
  IN @Doc_id char( 128 ),
  IN @Lock_Type char( 1 ),
  IN @AutoCommit bit DEFAULT  0 ,
  IN @RaisError bit DEFAULT  1 
)
BEGIN
  DECLARE @Connect_id unsigned int;
  DECLARE @Cur_Connect_id unsigned int;
  DECLARE @Cur_User_Name char( 128 );
  DECLARE @Lock_Date timestamp;

  IF IsNull(@Lock_Type, '') NOT IN ('+', '-')
  THEN
    IF @RaisError =  1 
    THEN
      RAISERROR  20000  'Указан неизвестный режим блокировки "' || @Lock_Type || '"';
    END IF;
    RETURN - 1 ;
  END IF;

  SET @Connect_id = CONNECTION_PROPERTY('Number');

  IF @Lock_Type = '+'
  THEN
    SELECT Connect_id, User_Name, Lock_Date
    INTO @Cur_Connect_id, @Cur_User_Name, @Lock_Date
    FROM DBA.Doc_Lock
    WHERE Table_Name = @Table_Name AND Doc_id = @Doc_id;

    IF @Cur_Connect_id IS NOT NULL AND @Cur_Connect_id <> @Connect_id
    THEN
      IF @AutoCommit =  1 
      THEN
        ROLLBACK;
      END IF;
      IF @RaisError =  1 
      THEN
        RAISERROR  20000  'Документ уже заблокирован пользователем "' || @Cur_User_Name || '" (' ||
                        @Cur_Connect_id || ') с ' || DateFormat(@Lock_Date, 'dd.mm.yyyy hh:mm');
      END IF;
      RETURN - 1 ;
    END IF;

    IF @Cur_Connect_id IS NULL
    THEN
      INSERT INTO DBA.Doc_Lock (Table_Name, Doc_id, Connect_id)
      VALUES (@Table_Name, @Doc_id, @Connect_id);
    END IF;

    IF @AutoCommit =  1 
    THEN
      COMMIT;
    END IF;
  ELSE
    DELETE FROM DBA.Doc_Lock
    WHERE Table_Name = @Table_Name AND Doc_id = @Doc_id AND Connect_id = @Connect_id;

    IF @@ROWCOUNT =  0 
    THEN
      IF @AutoCommit =  1 
      THEN
        ROLLBACK;
      END IF;

      IF @RaisError =  1 
      THEN
        RAISERROR  20000  'Блокировка документа отсутствует';
      END IF;
      RETURN - 1 ;
    END IF;

    IF @AutoCommit =  1 
    THEN
      COMMIT;
    END IF;
  END IF;
END;
COMMENT ON PROCEDURE "DBA"."sp_Doc_Lock" IS 'Заблокировать или разблокировать документ';

CREATE EVENT "Doc_Lock_DB_Startup" TYPE "DatabaseStart"
HANDLER
BEGIN 
  TRUNCATE TABLE DBA.Doc_Lock;
  COMMIT;
END;
COMMENT ON EVENT "Doc_Lock_DB_Startup" IS 'Очистить блокировки при запуске БД';

CREATE EVENT "Doc_Lock_Proccess_Disconnect" TYPE "Disconnect"
HANDLER
BEGIN 
  DECLARE @Connect_id unsigned int;
  SET @Connect_id = EVENT_PARAMETER('ConnectionID');

  DELETE FROM DBA.Doc_Lock
  WHERE Connect_id = @Connect_id;

  COMMIT;
END;
COMMENT ON EVENT "Doc_Lock_Proccess_Disconnect" IS 'Удаление логических блокировок по отключаемому пользователю';

UPDATE Table
SET ...
WHERE ID = @ID AND LastTime = @LastTime;

IF @@ROWCOUNT =  0 
THEN
  RAISERROR  20000  'Извините, но документ уже был изменен другим пользователем';
END IF;

    SELECT Connect_id, User_Name, Lock_Date
    INTO @Cur_Connect_id, @Cur_User_Name, @Lock_Date
    FROM asc_sys.Doc_Lock WITH (READUNCOMMITTED)
    WHERE Table_Name = @Table_Name AND Doc_id = @Doc_id;