MySQL trigger to target an attribute of a column

Question

I am working with an overlap super/subtype relationship dealing with person(s) in my DB. What I would like to do is have the overlapping subtypes insert new rows when the supertype gains a new row. I have attached my LRD to clarify the relationship. LRD I would like to create a trigger that inserts new person rows into the correct subtype based on the attributes employee/user in the person table. The code I have attempted so far gives me an error upon inserting rows into person noting "employee column does not exist". I would assume this is because this code is trying to use the if statement for the subtypes where it is in fact absent.

I would appreciate any feedback. Table Details

    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;

Trigger Code

 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

I ended up figuring out two methods to solve my issue. I ended up altering my 'employee' and 'participant' into boolean/tinyint data types.

    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;

After that alteration I decided to try and break up the one trigger into two. This was successful.

Type 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 ;

After inplementing that first option I realized the ELSEIF would allow me to not split the two and create a single trigger.

Type 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 ;

Answer 2

This may work for you.

First off, I think to have the AUTO_INCREMENT attribute on columns EMPLOYEE.eperson_id and PARTICIPANT.pperson_id is not needed.

Since both of those columns are FOREIGN KEYS and are referencing back to the person_id column of table PERSON, they need to have, and will be getting, their values from that column through the TRIGGER anyway so no need to autoincrement them in the tables. So I would change that.

This TRIGGER should work with populating both tables EMPLOYEE and PARTICIPANT after INSERT on table PERSON:

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 ;

Hope this helps you.