Question

我在psql数据库中不断收到此错误；

bikefacility=# ERROR:  syntax error at or near "c"
bikefacility-# LINE 1: c
bikefacility-#         ^
bikefacility-# bikefacility=# ALTER TABLE bicycle ADD CONSTRAINT fk_maintenance_contact_person FOREIGN KEY (maintenance_contact_person) REFERENCES maintenance(maintenance_contact_person);
ERROR:  syntax error at or near "ERROR"
LINE 1: ERROR:  syntax error at or near "c"
        ^
bikefacility=# ERROR:  column "maintenance_contact_person" referenced in foreign key constraint does not exist
bikefacility-# bikefacility=# ALTER TABLE bicycle ADD CONSTRAINT fk_rental_period FOREIGN KEY (rental_period) REFERENCES rental(rental_period);
ERROR:  syntax error at or near "ERROR"
LINE 1: ERROR:  column "maintenance_contact_person" referenced in fo...
        ^
bikefacility=# ERROR:  column "rental_period" referenced in foreign key constraint does not exist
bikefacility-# bikefacility=# ALTER TABLE bicycle ADD CONSTRAINT fk_terminal_id FOREIGN KEY (terminal_id) REFERENCES terminal(terminal_id);
ERROR:  syntax error at or near "ERROR"
LINE 1: ERROR:  column "rental_period" referenced in foreign key con...
        ^
bikefacility=# ERROR:  column "terminal_id" referenced in foreign key constraint does not exist

这是我的代码。正如您在此处看到的那样，我已经在代码中创建了相同样式的外键。

CREATE TABLE member (
  member_id INTEGER PRIMARY KEY,
  member_fname VARCHAR(15) NOT NULL,
  member_lname VARCHAR(15) NOT NULL,
  member_status VARCHAR(15) NOT NULL,
  member_address VARCHAR(10) NOT NULL,
  member_email VARCHAR(30) NOT NULL
);

CREATE TABLE bicycle (
  bicycle_id INTEGER PRIMARY KEY,
  bicycle_brand VARCHAR(25) NOT NULL,
  bicycle_model VARCHAR(25) NOT NULL,
  bicycle_colour VARCHAR(15) NOT NULL,
  bicycle_type VARCHAR(20) NOT NULL,
  bicycle_size VARCHAR(10) NOT NULL,
  bicycle_availability VARCHAR(20) NOT NULL

);

ALTER TABLE bicycle ADD CONSTRAINT fk_bicycle_pickup_date FOREIGN KEY (bicycle_pickup_date) REFERENCES rental(bicycle_pickup_date) >MATCH FULL;
ALTER TABLE bicycle ADD CONSTRAINT fk_maintenance_contact_person FOREIGN KEY (maintenance_contact_person) REFERENCES maintenance(maintenance_contact_person);
ALTER TABLE bicycle ADD CONSTRAINT fk_terminal_id FOREIGN KEY (terminal_id) REFERENCES terminal(terminal_id);
ALTER TABLE bicycle ADD CONSTRAINT fk_rental_period FOREIGN KEY (rental_period) REFERENCES rental(rental_period);

CREATE TABLE sponsor (
  sponsor_id INTEGER PRIMARY KEY,
  sponsor_name VARCHAR(15) NOT NULL,
  sponsor_contact VARCHAR(30) NOT NULL,
  sponsor_period DATE NOT NULL,
  sponsor_address VARCHAR(50) NOT NULL,
  sponsor_fee DECIMAL (6, 2) NOT NULL
);

CREATE TABLE terminal (
  terminal_id INTEGER PRIMARY KEY,
  terminal_address VARCHAR(50) NOT NULL,
  terminal_minstorage VARCHAR(50) NOT NULL,
  terminal_maxstorage VARCHAR(50) NOT NULL
);

CREATE TABLE rental (
  rental_no INTEGER PRIMARY KEY,
  rental_period DATE NOT NULL,
  bicycle_pickup_date DATE NOT NULL
);

它说这些列不存在，但我知道它们存在，因为它们就在那儿！有人可以帮我吗？提前致谢！

Answer 1

对于PostgreSQL，外键的语法不正确。例如，ALTER TABLE bicycle ADD CONSTRAINT fk_terminal_id FOREIGN KEY (terminal_id) REFERENCES terminal(terminal_id);要求自行车中有一个字段，名为terminal_id，因为您查询中的前一个terminal_id引用了自行车表，自行车表中应引用终端表中的terminal_id。

这是外键的简短教程。 https://www.postgresqltutorial.com/postgresql-foreign-key/

最好的问候，
比尼亚尼

Answer 2

您的架构非常混乱。

没有表maintenance，但您尝试对其进行引用。
必须先创建rental之类的外部表，然后才能对其进行fk引用。
您必须在引用的表中具有命名字段。表bicycle_pickup_date中没有字段maintenance_contact_person，terminal_id，rental_period或bicycle.
您的fk参考文献通常听起来很奇怪。您是否真的希望每辆自行车只能租一次？也许您是说租车是指一辆单车？

此外，您的命名约定非常多余。无需在每个字段名称中重复表名，只需在代码中添加不必要的内容即可。

外键约束不存在错误

2 个答案: