为什么下面的外键约束(虽然可以正常执行),但SQLite没有强制执行?我该如何强制执行这种关系?
CREATE TABLE User (
UserID TEXT Unique NOT NULL PRIMARY KEY,
FirstName TEXT NOT NULL,
LastName TEXT NOT NULL,
Username TEXT NOT NULL,
Password TEXT NOT NULL,
Email TEXT NOT NULL,
SignupDate TEXT NOT NULL
)
CREATE TABLE Category (
CategoryID TEXT Unique NOT NULL PRIMARY KEY,
UserID TEXT,
FOREIGN KEY(UserID) REFERENCES User(UserID)
)