我对 UPDATE BEFORE TRIGGER 有疑问

Question

我有以下表格：

CREATE TABLE Categorie
(categ_id NUMBER(5,0),
tip VARCHAR2(20));

CREATE TABLE Reteta
(reteta_id NUMBER(3),
nume VARCHAR2(100),
descriere VARCHAR2(200),
categ_id NUMBER(3,0),
vegetariana VARCHAR2(1) CHECK (vegetariana IN ('D','N')),
timp_preparare NUMBER(20,1),
portii NUMBER(3,1));

CREATE TABLE Set_ingrediente
(reteta_id NUMBER(3,0),
ingred_id NUMBER(3,0), 
cantitate NUMBER(5,2), 
um VARCHAR2(10) NOT NULL CHECK (um IN ('gr','ml','buc','lingurita','cana')), 
comentarii VARCHAR2(100)
);

CREATE TABLE Ingredient 
(ingred_id NUMBER(3,0), 
ingredient VARCHAR2(30));

以及以下 primary/foreign 键：

ALTER TABLE Categorie
MODIFY (categ_id CONSTRAINT categ_id_pk PRIMARY KEY NOT NULL);

ALTER TABLE Reteta
MODIFY(CONSTRAINT reteta_id_pk PRIMARY KEY (reteta_id));

ALTER TABLE Ingredient
MODIFY(CONSTRAINT ingred_id_pk PRIMARY KEY (ingred_id));

ALTER TABLE Set_ingrediente
MODIFY( CONSTRAINT reteta_id_fk FOREIGN KEY (reteta_id) REFERENCES Reteta(reteta_id) ON DELETE CASCADE);

ALTER TABLE Set_ingrediente
MODIFY( CONSTRAINT ingred_id_fk FOREIGN KEY (ingred_id) REFERENCES Ingredient(ingred_id) ON DELETE CASCADE);

我必须编写一个触发器：如果食谱中使用了 'oil' 成分，请确保不能更改素食列。这是我试过但不起作用的触发器：

CREATE OR REPLACE TRIGGER tr_oil BEFORE UPDATE
ON Reteta
FOR EACH ROW BEGIN
DECLARE
 ingredient_var ingredient.ingredient%type;
 SELECT ingredient
 INTO ingredient_var
 FROM Ingredint
 WHERE ingred_id=
 (SELECT ingred_id
 FROM Set_ingrediente
 WHERE reteta_id=NEW.reteta_id);
 IF ingredient_var='oil' THEN  
SET NEW.vegetariana = OLD.vegetariana;
END IF;
END;

Answer 1

这太奇怪了；到触发代码为止，您发布的所有内容都完美所以我无法想象当涉及到充满错误的触发器时出了什么问题（错位begin，无效table 名称，:new 伪记录缺少冒号，...）。好像两个不同的人写了你贴的两段代码。

无论如何：

SQL> CREATE OR REPLACE TRIGGER tr_oil
  2    BEFORE UPDATE ON Reteta
  3    FOR EACH ROW
  4  DECLARE
  5    ingredient_var ingredient.ingredient%type;
  6  BEGIN
  7    SELECT ingredient
  8      INTO ingredient_var
  9      FROM Ingredient
 10      WHERE ingred_id = (SELECT ingred_id
 11                         FROM Set_ingrediente
 12                         WHERE reteta_id = :NEW.reteta_id);
 13
 14    IF ingredient_var='oil' THEN
 15       :NEW.vegetariana := :OLD.vegetariana;
 16     END IF;
 17  END;
 18  /

Trigger created.

SQL>

我对 UPDATE BEFORE TRIGGER 有疑问

I have a problem with an UPDATE BEFORE TRIGGER

oracle

triggers

plsql