引用在SQL中不起作用的外键

Question

我试图引用两个独立的表来创建第三个表，但是SQL说在FOREIGN附近有一个语法错误

import sqlite3 as db
connection = db.connect("doctor_who_database")

cursor = connection.cursor()

cursor.execute("""CREATE TABLE IF NOT EXISTS doctor_who_database(
item_id TEXT PRIMARY KEY,
item TEXT)""")

cursor.execute("""CREATE TABLE IF NOT EXISTS doctor_who_database2(
person_id TEXT PRIMARY KEY,
season TEXT,
person TEXT)""")



cursor.execute("""CREATE TABLE IF NOT EXISTS doctor_who_database3(
id TEXT PRIMARY KEY,
item TEXT,
season TEXT,
person TEXT)""")

cursor.execute("""FOREIGN KEY(item_id) REFERENCES doctor_who_database(item_id)""")

Answer 1

FOREIGN KEY中的字段必须存在于创建FK的表中，item_id不是doctor_who_database3中的字段，FOREIGN KEY本身也不是命令，例如，它应该放在CREATE TABLE中

cursor.execute("""CREATE TABLE IF NOT EXISTS doctor_who_database3(
id TEXT PRIMARY KEY,
item TEXT,
season TEXT,
person TEXT,
FOREIGN KEY(id) REFERENCES doctor_who_database(item_id)""")