MySQL 触发器以列的属性为目标

Question

我正在处理与我的数据库中的人打交道的重叠 super/subtype 关系。我想要做的是让重叠的子类型在超类型获得新行时插入新行。我已经附上我的LRD来澄清关系。 LRD 我想创建一个触发器，根据人员 table 中的属性 employee/user 将新的人员行插入到正确的子类型中。到目前为止，我尝试的代码在将行插入 person noting "employee column does not exist" 时给我一个错误。我会假设这是因为这段代码试图对实际上不存在的子类型使用 if 语句。

如果有任何反馈，我将不胜感激。 Table 详情

    CREATE TABLE PERSON
(person_id int(10) not null AUTO_INCREMENT,
first_name varchar(15) not null,
last_name varchar(15) not null,
employee char(1),
participant char(1),
CONSTRAINT person_pk PRIMARY KEY (person_id))
ENGINE=InnoDB;

CREATE TABLE EMPLOYEE
(eperson_id int(10) not null AUTO_INCREMENT,
enterprise_email varchar(30),
manager_id int(10),
CONSTRAINT employee_pk PRIMARY KEY (eperson_id),
CONSTRAINT employee_fk1 FOREIGN KEY(eperson_id) REFERENCES PERSON(person_id) ON update cascade,
CONSTRAINT employee_fk2 FOREIGN KEY(manager_id) REFERENCES EMPLOYEE(eperson_id) ON update cascade)
ENGINE=InnoDB;

 CREATE TABLE PARTICIPANT
(pperson_id int(10) not null AUTO_INCREMENT,
city varchar(30),
state varchar(2),
zip int(5),
sign_up_date date,
termination_date date,
CONSTRAINT participant_pk PRIMARY KEY (pperson_id),
CONSTRAINT participant_fk FOREIGN KEY(pperson_id) REFERENCES PERSON(person_id) ON update cascade)
ENGINE=InnoDB;

触发码

 DELIMITER //
    CREATE TRIGGER subtype_creator
    AFTER INSERT ON PERSON 
    FOR EACH ROW 
BEGIN
    IF  (employee = ‘e’ ) THEN
    INSERT INTO EMPLOYEE
    SET eperson_id = NEW.person_id,
        last_name = NEW.last_name,
        enterprise_email = NULL,
        manager_id = NULL;
   IF  (participant = ‘p’ )THEN
  INSERT INTO PARTICIPANT
    SET pperson_id = NEW.person_id,
    city=NULL,
    state = NULL,
    zip = NULL,
    sign_up_date =NULL,
    termination_date = NULL;
    END IF;
END IF;
END//
DELIMITER ;

Answer 1

这可能对你有用。

首先，我认为不需要在列 EMPLOYEE.eperson_id 和 PARTICIPANT.pperson_id 上设置 AUTO_INCREMENT 属性。

因为这两列都是 FOREIGN KEYS 并且引用回 table PERSON 的 person_id 列，所以他们需要并且将会得到，它们的值从该列到 TRIGGER 无论如何都不需要在 table 中自动递增它们。所以我会改变它。

这个 TRIGGER 应该可以在 table PERSON INSERT 之后填充 tables EMPLOYEE 和 PARTICIPANT :

DELIMITER //
    CREATE TRIGGER subtype_creator
    AFTER INSERT ON PERSON 
    FOR EACH ROW 
BEGIN
    INSERT INTO EMPLOYEE(eperson_id, enterprise_email, manager_id)
    VALUES(NEW.person_id, NULL, NULL);
    INSERT INTO PARTICIPANT(pperson_id, city, state, zip, sign_up_date, termination_date)
    VALUES(NEW.person_id, NULL, NULL, NULL, NULL, NULL);
END//
DELIMITER ;

希望对您有所帮助。

Answer 2

我最终想出了两种方法来解决我的问题。我最终将 'employee' 和 'participant' 更改为 boolean/tinyint 数据类型。

    CREATE TABLE PERSON
(person_id int(10) not null AUTO_INCREMENT,
first_name varchar(15) not null,
last_name varchar(15) not null,
employee tinyint(1),
participant tinyint(1),
CONSTRAINT person_pk PRIMARY KEY (person_id))
ENGINE=InnoDB;

在那次改动之后，我决定尝试将一个触发器分成两个。这是成功的。

类型 1

    DELIMITER //
CREATE TRIGGER employee_creator
    AFTER INSERT ON PERSON 
    FOR EACH ROW 
BEGIN
    IF  (NEW.employee = 1 ) THEN
            INSERT INTO EMPLOYEE
        SET eperson_id = NEW.person_id,
            last_name = NEW.last_name,
                enterprise_email = NULL,
                manager_id = NULL;
    END IF;
END//
DELIMITER ;

DELIMITER //
CREATE TRIGGER participant_creator
    AFTER INSERT ON PERSON 
    FOR EACH ROW 
BEGIN
    IF  (NEW.participant =0 )THEN
         INSERT INTO PARTICIPANT
         SET pperson_id = NEW.person_id,
         city=NULL,
         state = NULL,
             zip = NULL,
         sign_up_date =NULL,
         termination_date = NULL;
        END IF;
END//
DELIMITER ;

在实施第一个选项后，我意识到 ELSEIF 将允许我不拆分两者并创建一个触发器。

类型 2

DELIMITER //
CREATE TRIGGER employee_creator
    AFTER INSERT ON PERSON 
    FOR EACH ROW 
BEGIN
    IF  (NEW.employee = 1 ) THEN
            INSERT INTO EMPLOYEE
        SET eperson_id = NEW.person_id,
            last_name = NEW.last_name,
                enterprise_email = NULL,
                manager_id = NULL;

    ELSEIF  (NEW.participant =0 )THEN
         INSERT INTO PARTICIPANT
         SET pperson_id = NEW.person_id,
         city=NULL,
         state = NULL,
             zip = NULL,
         sign_up_date =NULL,
         termination_date = NULL;
        END IF;
END//
DELIMITER ;

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