Question

此触发器（Oracle 12c）旨在阻止列（价格）大于变量的表（MainTable aka Room）中行的插入和更新。变量的值取决于另一列（类型）。有三种类型（S，D，K），＆＃39;类型的允许最大价格分别为100,150和200。触发器通过引用具有两列和三行的域表（DomainTable aka RoomType）来工作，如下所示[roomTypeCode（S，D，K），maxPrice（100,150,200）]并确保：

...如果新的MainTable.type =＆＃39; S＆＃39;，那么新的MainTable.price＆lt; DomainTable.maxPrice（S）;

...如果新的MainTable.type =＆＃39; D＆＃39;，那么新的MainTable.price＆lt; DomainTable.maxPrice（d）;

...如果新的MainTable.type =＆＃39; K＆＃39;，那么新的MainTable.price＆lt; DomainTable.maxPrice（K）;

这是我的尝试不起作用。


CREATE TRIGGER Room_Type_Price_Range
  BEFORE INSERT OR UPDATE ON room
  REFERENCING NEW AS newRec
  FOR EACH ROW
  DECLARE
    SELECT maxPrice INTO singleRmMax FROM RoomType WHERE RoomTypeCode = 'S';
    SELECT maxPrice INTO doubleRmMax FROM RoomType WHERE RoomTypeCode = 'D';
    SELECT maxPrice INTO kingRmMax FROM RoomType WHERE RoomTypeCode = 'K';
  BEGIN
     IF (   (:newRec.type = 'S' AND :newRec.price > singleRmMax)
        OR  (:newRec.type = 'D' AND :newRec.price > doubleRmMax)
        OR  (:newRec.type = 'K' AND :newRec.price > kingRmMax)
        )
        RAISE_APPLICATION_ERROR(-20001, 'Price constraint violated.  
          \nCannot Insert/Update in this table.');
  END;

我的错误讯息：


04098. 00000 -  "trigger '%s.%s' is invalid and failed re-validation"
*Cause:    A trigger was attempted to be retrieved for execution and was
           found to be invalid.  This also means that compilation/authorization
           failed for the trigger.
*Action:   Options are to resolve the compilation/authorization errors,
           disable the trigger, or drop the trigger.

感谢您的帮助！

Answer 1

当您创建触发器时，您会看到一条消息，例如＆＃39;编译时带有警告＆＃39;或者＆＃39;错误：检查编译器日志＆＃39;。此时，您可以show errors查看编译失败的原因，或查看SQL Developer的编译器日志窗口。

当您插入或更新the invalid trigger is automatically recompiled时，但由于它仍然无效，您会收到ORA-04098错误。您仍然可以通过查询user_errors视图来查看错误：

select line, position, text
from user_errors
where type = 'TRIGGER'
and name = 'ROOM_TYPE_PRICE_RANGE'
order by sequence;

你的代码中有三个错误;仅显示每个的第一行：

LINE POSITION TEXT
---- -------- -------------------------------------------------------------------------------------------------
   2        5 PLS-00103: Encountered the symbol "SELECT" when expecting one of the following:
  10        9 PLS-00103: Encountered the symbol "RAISE_APPLICATION_ERROR" when expecting one of the following:
  11       50 PLS-00103: Encountered the symbol ";" when expecting one of the following:

正如David Faber在评论中指出的那样，第一个错误是因为你的声明部分中有一个select语句;或许在这一点上审查the structure of a subprogram会很有用。

第二个错误是因为您的IF没有THEN个关键字，第三个错误是因为您没有END IF。只需清理你要声明的内容并正确填充变量，你就会得到类似的东西：

DECLARE
  singleRmMax RoomType.MaxPrice%TYPE;
  doubleRmMax RoomType.MaxPrice%TYPE;
  kingRmMax RoomType.MaxPrice%TYPE;
BEGIN
  SELECT maxPrice INTO singleRmMax FROM RoomType WHERE RoomTypeCode = 'S';
  SELECT maxPrice INTO doubleRmMax FROM RoomType WHERE RoomTypeCode = 'D';
  SELECT maxPrice INTO kingRmMax FROM RoomType WHERE RoomTypeCode = 'K';

  IF (   (:newRec.type = 'S' AND :newRec.price > singleRmMax)
    OR  (:newRec.type = 'D' AND :newRec.price > doubleRmMax)
    OR  (:newRec.type = 'K' AND :newRec.price > kingRmMax)
    ) THEN
    RAISE_APPLICATION_ERROR(-20001, 'Price constraint violated.  
      \nCannot Insert/Update in this table.');
  END IF;
END;

你真的不需要三个变量，你可以只查询你感兴趣的房间类型：

DECLARE
  roomTypeMax RoomType.MaxPrice%TYPE;
BEGIN
  SELECT maxPrice INTO roomTypeMax
  FROM RoomType
  WHERE RoomTypeCode = :newRec.type;

  IF :newRec.price > roomTypeMax THEN
    RAISE_APPLICATION_ERROR(-20001,
      'Price constraint violated. Cannot Insert/Update in this table.');
  END IF;
END;

我还从错误消息中取出\n，因为插件可能会将其视为两个字面字符而不是换行符。

您可能还想考虑抓住no_data_found并提出自己的例外情况，因为这表明新房型并不存在，因此无论如何都无效。

如何使用Oracle触发器（和域表）代替检查约束来强制列范围

1 个答案: