python sqlite 外键未在级联上删除

Question

所以我有 2 个文件，一个客户端和一个数据库 class:

import sqlite3
from os.path import isfile

class Database:
 def __init__(self, db_name):
    self.db_name = db_name
    self.check = self.__check_db()
    self.conn = sqlite3.connect(self.db_name, check_same_thread=False)
    self.cursor = self.conn.cursor()
    if not self.check:
        self.__create_db()

 def query(self, query, args=()):
    self.cursor.execute(query, args)
    result = self.cursor.fetchall()
    self.conn.commit()
    return result

 def __check_db(self):
    return isfile(self.db_name)

 def __create_db(self):
    self.cursor.executescript("""
                        PRAGMA FOREIGN_KEYS = ON;
                        
                        CREATE TABLE utilizadores (id INTEGER PRIMARY KEY, nome TEXT, senha TEXT);
                        
                        CREATE TABLE artistas (id INTEGER PRIMARY KEY, id_spotify TEXT, nome TEXT);
                        
                        CREATE TABLE musicas (id INTEGER PRIMARY KEY, id_spotify TEXT, nome TEXT, id_artista INTEGER, FOREIGN KEY(id_artista) REFERENCES artistas(id) ON DELETE CASCADE);
                                                        
                        CREATE TABLE avaliacoes (id INTEGER PRIMARY KEY, sigla TEXT, designacao TEXT);
                            
                        CREATE TABLE playlists (id_user INTEGER, id_musica INTEGER, id_avaliacao INTEGER, PRIMARY KEY (id_user, id_musica), FOREIGN KEY(id_user) REFERENCES utilizadores(id) ON DELETE CASCADE, FOREIGN KEY(id_musica) REFERENCES musicas(id) ON DELETE CASCADE, FOREIGN KEY(id_avaliacao) REFERENCES avaliacoes(id) ON DELETE CASCADE);
                        
                        INSERT INTO avaliacoes (id, sigla, designacao) VALUES (1, "M", "Medíocre"), (2, "m", "Mau"), (3, "S", "Suficiente"), (4, "B", "Boa"), (5, "MB", "Muito Boa");
                        """)

和客户；

from database import Database

db = Database("spotify.db")

db.query("insert into artistas (id_spotify, nome) values (?, ?)", ("1", "The Beatles"))
db.query("insert into musicas (id_spotify, nome, id_artista) values (?, ?, ?)", ("m1", "Hey Jude", 1))

db.query("delete from artistas where id = ?", (1,))

如果我因为外键而执行最后一个查询，它也应该删除音乐，但由于某种原因它没有。我不知道为什么这样做，因为我有 PRAGMA fk = on 并且我在同一个连接上

艺术家 --> 艺术家

音乐 --> 音乐

Answer 1

PRAGMA FOREIGN_KEYS = ON 在 每个连接的基础上运行 这意味着您必须为您获得的每个连接对象设置它（如果您想要它提供的行为，否则不要设置它，因为它可能会降低性能）。

里面Databaseclass定义：

def set_foreign_keys(self)
    self.conn.execute("PRAGMA FOREIGN_KEYS = ON")

并在客户端使用：

from database import Database

db = Database("spotify.db")
db.set_foreign_keys()

db.query("insert into artistas (id_spotify, nome) values (?, ?)", ("1", "The Beatles"))
db.query("insert into musicas (id_spotify, nome, id_artista) values (?, ?, ?)", ("m1", "Hey Jude", 1))

db.query("delete from artistas where id = ?", (1,))

python sqlite 外键未在级联上删除

python sqlite foreing keys not deleting on cascade

python

python-3.x

sqlite

foreign-keys

sql-delete