Android On Delete Cascade 无法正常工作

Question

我正在制作 android 应用程序，其中我在一个开放的帮助程序类中制作了 5 个表。当我在我的模式中有 ON DELETE CASCADE 时，我遇到了问题。我知道 ON DELETE CASCADE 的概念。在这里，我正在复制我的两个表中的一个。

private static final String MEDICINE_TABLE  = "create table medicine_details (_mid integer primary key autoincrement, "
                                                    + " medicine_name text, type text, take_with text, m_did integer not null,"
                                                    + "FOREIGN KEY(m_did) REFERENCES doctor_details(did)"
                                                    + " ON DELETE CASCADE" + ");";

private static final String SCH_TAB         = "CREATE TABLE schedule_details(sid INTEGER PRIMARY KEY AUTOINCREMENT, "
                                                    + "medi_stdate TEXT,medi_end_date TEXT,time_sch TEXT,rept TEXT, alarm_id NUMBER, "
                                                    + "u_id integer not null, doc_id integer not null, mid integer not null, "
                                                    + "FOREIGN KEY(u_id) REFERENCES member_details(_id)"
                                                    + " ON DELETE CASCADE,"
                                                    + "FOREIGN KEY(doc_id) REFERENCES doctor_details(did)"
                                                    + " ON DELETE CASCADE,"
                                                    + "FOREIGN KEY(mid) REFERENCES medicine_details(_mid)"
                                                    + " ON DELETE CASCADE" + ");";

每当我尝试从医学中删除时，它只会从医学表中删除，而不是从时间表中删除。这里 medicine table 是 master table，schedule table 是 child table。

Answer 1

您必须覆盖 open() 方法，如下例所示:

    @Override
public void onOpen(SQLiteDatabase db) {
    super.onOpen(db);
    if (!db.isReadOnly()) {
        db.execSQL("PRAGMA foreign_keys=ON;");
    }
}

最好的问候