我想在表中添加一個新的模型實例，但它總是顯示“無法添加或更新子行：外鍵約束失敗”。我已經檢查過 userTable 是否有 UserId。這是用戶表的內容：{ "ID": 1, "UserId": "001201400047", "UserName": "User A", "UserPass": "admin", "UserStatus": "admin" },{ "ID": 2, "UserId": "100100010000", "UserName": "User B", "UserPass": "user", "UserStatus": "student" }from peewee import *from datetime import datetimedatabase = MySQLDatabase('AAS', **{'passwd': 'admin', 'charset': 'utf8', 'user': 'yusfa', 'use_unicode': True})class UnknownField(object):    def __init__(self, *_, **__): passclass BaseModel(Model):    class Meta:        database = databaseclass Classtable(BaseModel):    classid = CharField(column_name='ClassId', primary_key=True)    lecturerid = ForeignKeyField(column_name='LecturerId', model=Lecturertable)    roomid = ForeignKeyField(column_name='RoomId', model=Roomtable)    subjectid = ForeignKeyField(column_name='SubjectId', model=Subjecttable)    class Meta:        table_name = 'classTable'class Usertable(BaseModel):    id = AutoField(column_name='ID')    userid = CharField(column_name='UserId', unique=True)    username = CharField(column_name='UserName', null=True)    userpass = CharField(column_name='UserPass', null=True)    userstatus = CharField(column_name='UserStatus', null=True)    class Meta:        table_name = 'userTable'class Attendancetable(BaseModel):    classid = ForeignKeyField(column_name='ClassId', model=Classtable, null=True)    date = DateTimeField(column_name='Date', null=True)    id = AutoField(column_name='ID')    userid = ForeignKeyField(column_name='UserId', model=Usertable, null=True)我希望在 Attendancetable 中會有一個新的模型實例，但實際輸出是 peewee.IntegrityError: (1452, '無法添加或更新子行：外鍵約束失敗 ( AAS. attendanceTable, CONSTRAINT fk_attendanceTable_1FOREIGN KEY ( UserId) REFERENCES userTable( userid))' ）。