PostgreSQL的关键约束错误

Question

我尝试为postgresql创建代码

CREATE TABLE kaart (
    kaartid integer NOT NULL,
    naam character varying,
    saldo real,
    kaarthouderid integer
);


CREATE TABLE kaart_product (
    kaartkaartid integer,
    productid2 integer
);

CREATE TABLE kaarthouder (
    id integer NOT NULL,
    naam character varying(255),
    naw character varying(255),
    geslacht "char"
);

CREATE TABLE product (
    naam character varying,
    id integer NOT NULL
);


ALTER TABLE ONLY kaart
    ADD CONSTRAINT kaart_pkey PRIMARY KEY (kaartid);

ALTER TABLE ONLY kaarthouder
    ADD CONSTRAINT kaarthouder_pkey PRIMARY KEY (id);

ALTER TABLE ONLY product
    ADD CONSTRAINT product_pkey PRIMARY KEY (id);

ALTER TABLE ONLY kaart
    ADD CONSTRAINT kaartco FOREIGN KEY (kaartid) REFERENCES kaarthouder(id) ON UPDATE CASCADE ON DELETE CASCADE;

ALTER TABLE ONLY kaart_product
    ADD CONSTRAINT kaartkaartidco FOREIGN KEY (kaartkaartid) REFERENCES kaart(kaartid) ON UPDATE CASCADE ON DELETE CASCADE;

ALTER TABLE ONLY kaart_product
    ADD CONSTRAINT productidco FOREIGN KEY (kaartkaartid) REFERENCES product(id) ON UPDATE CASCADE ON DELETE CASCADE;

INSERT INTO kaart VALUES (1, 'Sander',50.00 ,1);
INSERT INTO kaart_product VALUES (1,1);
INSERT INTO kaarthouder VALUES (1, 'Sander','test,testing','man');
INSERT INTO product VALUES ('studentenproduct',1);

但是，每当我尝试运行它时，都会出现此错误：

23503：在表“ kaart”上插入或更新违反了外键约束“ kaartco”

但是我真的不知道为什么会发生这种情况，因为它与它下面的其他外键相同

有人可以帮我解决这个问题吗？

Answer 1

您尝试链接到尚不存在的产品和kaart。

移动：

INSERT INTO kaart_product VALUES (1,1);

下两行：

INSERT INTO product VALUES ('studentenproduct',1);

那应该为您完成工作。 尝试在Google上搜索forgein关键约束及其工作方式。