오류 코드 1215가 나타나는 이유는 무엇입니까?

Question

CREATE TABLE speler 
(
    scode   INT(5)  NOT NULL AUTO_INCREMENT, 
    naam   CHAR(20) NOT NULL, 
    adres   CHAR(50) , 
    postcode  CHAR(6) , 
    woonplaats  CHAR(15) , 
    tel_num  INT(11)  NOT NULL, 
    email   CHAR(40) NOT NULL, 
    bekende_speler CHAR(3) NOT NULL, 
    rating   INT(3)  NOT NULL, 
    gewonnen_inleggeld VARCHAR(20) , 
    PRIMARY KEY (scode) 
) ENGINE=InnoDB; 


CREATE TABLE locatie (
    lcode  INT(5) NOT NULL AUTO_INCREMENT, 
    locatie   VARCHAR(55) NOT NULL, 
PRIMARY KEY (lcode)) ENGINE=InnoDB; 

CREATE TABLE toernooi (
tcode  INT(5) NOT NULL AUTO_INCREMENT, 
    type_spel VARCHAR(50) NOT NULL, 
    aantal_tafels INT(5) NOT NULL, 
    aantal_rondes INT(5) NOT NULL, 
    aantal_spelers INT(5) NOT NULL, 
    max_spelers  INT(5) NOT NULL, 
    datum  DATE NOT NULL, 
    tijd  VARCHAR(11) NOT NULL, 
    inleg_geld VARCHAR(21), 
    lcode  INT(5) NOT NULL, 
PRIMARY KEY (tcode), 
FOREIGN KEY (lcode) REFERENCES locatie(lcode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE 
) ENGINE=InnoDB; 

CREATE TABLE ronde (
    rcode  INT(5) NOT NULL AUTO_INCREMENT, 
    tcode  INT(5) NOT NULL, 
PRIMARY KEY (rcode), 
FOREIGN KEY (tcode) REFERENCES toernooi(tcode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE 
) ENGINE=InnoDB; 




CREATE TABLE tafel (
    tafelnr   INT(5) NOT NULL AUTO_INCREMENT, 
    aantal_fiches VARCHAR(255), 
    aantal_spelers INT(5) , 
    max_spelers  INT(5) NOT NULL, 
    rcode  INT(5) NOT NULL, 
PRIMARY KEY (tafelnr), 
FOREIGN KEY(rcode) REFERENCES ronde(rcode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE 
) ENGINE=InnoDB; 


CREATE TABLE masterclass 
(
    mcode   INT(5)  NOT NULL AUTO_INCREMENT, 
    kosten   VARCHAR(20) NOT NULL, 
    max_spelers  INT(3)  NOT NULL, 
    min_rating  INT(3)  NOT NULL, 
    scode   INT(5)  NOT NULL, 
    lcode   INT(5)  NOT NULL, 
    PRIMARY KEY(mcode), 
    FOREIGN KEY(scode) REFERENCES speler(scode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE, 
    FOREIGN KEY(lcode) REFERENCES locatie(lcode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE 
)ENGINE=InnoDB; 


CREATE TABLE inschrijving_masterclass 
(
scode   INT(5)  NOT NULL, 
mcode   INT(5)  NOT NULL, 
betaald   CHAR(3) NOT NULL, 
PRIMARY KEY(scode, mcode), 
FOREIGN KEY(scode) REFERENCES speler(scode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE, 
FOREIGN KEY (mcode) REFERENCES masterclass(mcode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE 
)ENGINE=InnoDB; 






CREATE TABLE inschrijving_toernooi 
(
    scode   INT(5)  NOT NULL, 
    tcode   INT(5)  NOT NULL, 
    Betaald   INT(3)  NOT NULL, 
    PRIMARY KEY(scode, tcode), 
    FOREIGN KEY(scode) REFERENCES speler(scode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE, 
    FOREIGN KEY(tcode) REFERENCES toernooi(tcode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE 
) ENGINE=InnoDB; 

CREATE TABLE ingeschreven_aan (
    scode  INT(5) NOT NULL, 
    tcode  INT(5) NOT NULL, 
    tafelnr  INT(5) NOT NULL, 
PRIMARY KEY(scode, tcode, tafelnr), 
FOREIGN KEY (scode) REFERENCES speler(scode) 
     ON DELETE SET NULL 
     ON UPDATE CASCADE, 
FOREIGN KEY (tcode) REFERENCES toernooi(tcode) 
     ON DELETE RESTRICT 
     ON UPDATE CASCADE, 
FOREIGN KEY (tafelnr) REFERENCES tafel(tafelnr) 
     ON DELETE SET NULL 
     ON UPDATE CASCADE 
) ENGINE=InnoDB; 

Answer 1

에 not null으로 일부 열을 정의했습니다. 그러나 조합하여 작동하지 않는 on delete set null도 정의했습니다.