如何使用 Oracle 触发器（和域 table）代替检查约束来强制执行列范围

Question

此触发器 (Oracle 12c) 旨在停止在 table（MainTable aka Room）中的行的插入和更新，其中列（价格）大于变量。变量的值取决于另一列（类型）。共有三种“类型”（S、D、K），“类型”允许的最高价格分别为 100、150 和 200。触发器通过引用具有两列和三行的域 table（DomainTable 又名 RoomType）来工作，如下所示 [roomTypeCode(S, D, K), maxPrice(100, 150, 200)] 并确保：

...如果新 MainTable.type = 'S'，则新 MainTable.price < DomainTable.maxPrice(S);

...IF new MainTable.type = 'D', THEN new MainTable.price < DomainTable.maxPrice(D);

...如果新 MainTable.type = 'K'，则新 MainTable.price < DomainTable.maxPrice(K);

我的尝试无效。


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;

我的错误信息：


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，您会看到类似 'compiled with warnings' 或 'Errors: check compiler log' 的消息。那时你可以做 show errors 查看编译失败的原因，或者查看 SQL 开发者的编译器日志 window.

当您插入或更新 the invalid trigger is automatically recompiled，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 视图来查看问题所在：

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

你的代码给出了三个错误；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，第一个错误是因为您的声明部分中有一个 select 语句；也许复习 the structure of a subprogram 在这一点上会有用。

第二个错误是因为您的 IF 没有 THEN 关键字，第三个错误是因为您也没有 END IF。只需清理您必须声明的内容并正确填充变量，您就会得到如下内容：

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;

虽然你真的不需要三个变量，你可以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;

我还从错误消息中删除了 \n，因为插入内容可能会将其视为两个文字字符而不是换行符。

您可能还想考虑捕获 no_data_found 并提出您自己的异常，因为这表明新房型不存在，因此在任何价格下均无效。

如何使用 Oracle 触发器（和域 table）代替检查约束来强制执行列范围

How to use Oracle trigger (and a domain table) in place of check constraint to enforce column range

sql

oracle

triggers

plsql

oracle-sqldeveloper