mysql - 为什么我会收到错误代码 1215？

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

not null您在 中定义了一些列ingeschreven_aan。但也定义了一个on delete set null不能组合使用的。