PL/SQL 无效标识符

Question

在“emprunter”表上创建触发器时，我试图比较来自另一个表“exemplaire.numexemplaire”的值，该表应该是一个整数。但我不断收到相同的错误：

• 错误(4,7): PL/SQL: SQL 语句被忽略
• 错误 (7,15): PL/SQL: ORA-00904: "EMPRUNTER"."NUMEXEMPLAIRE": 标识符无效

如何检索来自另一个表 (exemplaire.numexemplaire) 的字段的值？

CREATE OR REPLACE TRIGGER BIEmprunter
BEFORE INSERT OR UPDATE OF numexemplaire ON emprunter
FOR EACH ROW
DECLARE 
      livreEmpruntable    INTEGER;
BEGIN 
      SELECT  exemplaire.empruntable 
      INTO    livreEmpruntable
      FROM    exemplaire  
      WHERE   emprunter.numexemplaire = exemplaire.numexemplaire;

  IF livreEmpruntable != 1 THEN
    raise_application_error(-20000, 'exemplaire non empruntable');
  END if;
END;

更新 1

感谢您的回答，但我在尝试测试触发器时不断收到此错误...

SQL Error: ORA-04098: trigger 'EQUIPE10.ABONNEMENTPASAJOUR' is invalid and failed re-validation
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.

更新 2 再次感谢您的回答，触发器现在可以编译了。但是现在当我试图在插入值时让它工作但我一直收到错误，因为还没有数据......

INSERT INTO emprunter
  VALUES (2, 1, 18, '17-02-01', null);

Error report -
SQL Error: ORA-01403: no data found
ORA-06512: at "EQUIPE10.BIEMPRUNTER", line 4
ORA-04088: error during execution of trigger 'EQUIPE10.BIEMPRUNTER'
01403. 00000 -  "no data found"
*Cause:    No data was found from the objects.
*Action:   There was no data from the objects which may be due to end of fetch.

Answer 1

你想加入两个表：

CREATE OR REPLACE TRIGGER BIEmprunter
BEFORE INSERT OR UPDATE OF numexemplaire ON emprunter
FOR EACH ROW
DECLARE 
      livreEmpruntable    INTEGER;
BEGIN 
      SELECT  exemplaire.empruntable 
      INTO    livreEmpruntable
      FROM exemplaire 
      join emprunter
        ON  emprunter.numexemplaire = exemplaire.numexemplaire;

  IF livreEmpruntable != 1 THEN
    raise_application_error(-20000, 'exemplaire non empruntable');
  END if;
END;

此外，上述连接查询可能会返回多行，并且调用将导致异常（目前未捕获）

ORA-01422：精确提取返回的行数超过了请求的行数

Answer 2

我猜你想使用:new 来访问触发触发器的记录：

CREATE OR REPLACE TRIGGER BIEmprunter
BEFORE INSERT OR UPDATE OF numexemplaire ON emprunter
FOR EACH ROW
DECLARE 
      livreEmpruntable    INTEGER;
BEGIN 
      SELECT  exemplaire.empruntable 
      INTO    livreEmpruntable
      FROM    exemplaire  
      WHERE   :new.numexemplaire = exemplaire.numexemplaire;

  IF livreEmpruntable != 1 THEN
    raise_application_error(-20000, 'exemplaire non empruntable');
  END if;
END;