事务功能

Question

我需要将Informix函数转换为PostgreSQL。问题是我知道PostgreSQL不允许调用、开始、工作和提交函数，所以我不知道如何以这种方式处理异常和回滚。

要转换的函数如下所示：

CREATE PROCEDURE buyTicket(pFlightId LIKE transaction.flightId, pAmount LIKE transaction.amount) 
      DEFINE sqle, isame INTEGER; 
      DEFINE errdata CHAR(80); 
      ON EXCEPTION SET sqle, isame, errdata 
         ROLLBACK WORK; 
         IF sqle = -530 AND errdata LIKE '%chkfreespots%' THEN 
            RAISE EXCEPTION -746, 0, 'Not enough free spots';               
         ELSE 
            RAISE EXCEPTION sqle, isame, errdata; 
         END IF 
      END EXCEPTION; 
   BEGIN WORK; 
   INSERT INTO transaction VALUES (0, pFlightId, pAmount); 
   UPDATE tickets SET freeSpots= freeSpots - pAmount
      WHERE flightId = pFlightId; 
   COMMIT WORK; 
END PROCEDURE; 

Answer 1

在阅读了你的评论后，我终于解决了这个问题。下面是与我上面发布的Informix相同的PostgreSQL代码：

CREATE OR REPLACE FUNCTION buyTicket(pFlightId INT, pAmount INT)
RETURNS VOID AS $$
BEGIN
  INSERT INTO transaction(flightId,amount) VALUES (pFlightId, pAmount); 
  UPDATE tickets SET freeSpots = freeSpots - pAmount
  WHERE flightId = pFlightId; 
EXCEPTION
  WHEN others THEN
    IF sqlerrm LIKE '%chkfreespots%' THEN
       RAISE EXCEPTION  'Not enough free spots';
    ELSE
      RAISE;
    END IF;
END;
$$ LANGUAGE plpgsql;