Android On Delete Cascade无法正常工作

Question

我正在制作android应用程序，其中我在一个开放式帮助程序类中制作了5张表。 我在架构中有“删除级联”时遇到了问题。 我知道ON DELETE CASCADE的概念。 在这里，我要复制我的两个桌子之一。

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" + ");";

每当我尝试从药品中删除时，它仅从药品表中删除，而不从计划表中删除。 这里的药物表是主表，计划表是子表。

Answer 1

您必须重写方法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;");
    }
}

最好的祝福

Answer 2

在数据库的open()方法中，添加以下代码
mDb.execSQL("PRAGMA foreign_keys=ON;");