Question

我正在制作Android应用程序，其中我在一个开放助手类中制作了5个表。我正在我的架构中使用DELETE CASCADE时遇到问题。我知道ON DELETE CASCADE的概念。在这里，我复制了两张桌子中的一张。

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" + ");";

每当我尝试从药物中删除时，它仅从药物表中删除，而不是从计划表中删除。这里的医学表是主表，而日程表是子表。

Answer 1

您必须覆盖方法open()，如以下示例所示：

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

最好的问候

Answer 2

在您的数据库open()方法中添加以下代码
mDb.execSQL("PRAGMA foreign_keys=ON;");

Android On Delete Cascade无法正常工作

2 个答案: