Question

my DB like that. 我搜索了许多页面，视频，但我无法找到一个例子，我无法做到这个例子。在我的项目中，没有任何添加，删除和更新按钮。我的sqlite数据库中包含所有数据。

在这个程序中，我的主表将列在listview的第一个主要布局上。当我单击一行时，我必须在listview上的相关表上看到其他数据。（当我点击listview上的客户时，我会在另一个列表视图上看到所有订单。我桌子上的所有数据。）

我希望我解释了我的问题。是否有人会为我提供一个例子。

Answer 1

正如您已经了解客户，您可以执行一个非常简单的查询来获取可以构建/重新构建ListView的游标。

然后以下将返回这样一个光标： -

public Cursor getCustomerOrders(long customerref) {
        return this.getWritableDatabase().query("Orders",null,
                "CustomerID=?",
                new String[]{Long.toString(customerref)},
                null,null,null);
    }

customerref 是客户表的 ID 列中的值。

您将使用以下方法调用它（假设SQLiteOpenHelper子类名为DBHelper）： -

Cursor orderlist = getCustomerOrders(clicked_customer);

工作示例

活动

public class MainActivity extends AppCompatActivity {

    ListView customerlist;
    ListView orderlist;
    Cursor customers;
    Cursor orders;
    SimpleCursorAdapter sca_customers;
    SimpleCursorAdapter sca_orders;
    DBHelper dbh = new DBHelper(this);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        customerlist = (ListView) findViewById(R.id.customerlist);
        orderlist = (ListView) findViewById(R.id.orderlist);

        //Create some randomish data for 3 Customers
        Random rnd = new Random(System.currentTimeMillis());
        Cursor chkforempty = dbh.getWritableDatabase().query(DBHelper.CUSTOMERSTABLE,null,null,null,null,null,null);
        boolean chk = (chkforempty.getCount() > 0);
        chkforempty.close();
        if (!chk) {
            for (int i=0; i < 3; i++) {
                String suffix = Integer.toString(i);
                dbh.insertCustomer("Compnay" + suffix,"Name " + suffix, "Last Name " + suffix);
                int randomorders = rnd.nextInt(10) + 1;
                for (int i2=0; (i2 < randomorders) || (i2 < 10); i2++ ) {
                    dbh.insertOrder((long) i,"Destination " + Integer.toString(i2));
                }
            }
        }

        //Back to the real code
        customers = dbh.getCustomers();
        orders = dbh.getCustomerOrders(-1); // get none at first
        sca_customers = new SimpleCursorAdapter(this,
                android.R.layout.simple_list_item_1,
                customers,
                new String[]{DBHelper.CUSTOMER_COMPANY_COL},
                new int[]{android.R.id.text1},0);

        sca_orders = new SimpleCursorAdapter(this,
                android.R.layout.simple_list_item_1,
                orders,
                new String[]{DBHelper.ORDER_DESTINATION_COL},
                new int[]{android.R.id.text1},0);
        customerlist.setAdapter(sca_customers);
        orderlist.setAdapter(sca_orders);

        customerlist.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                orders = dbh.getCustomerOrders(l);
                sca_orders.swapCursor(orders);

            }
        });
    }
}

DBHelper.java（SQLiteOpenHelper子类）

public class DBHelper extends SQLiteOpenHelper {

    public static final String DBNAME = "mydatabase";
    private static final int DBVERSION = 1;
    public static final String CUSTOMERSTABLE = "customers";
    public static final String ORDERSTABLE = "orders";

    public static final String CUSTOMER_ID_COL = "_id";
    public static final String CUSTOMER_COMPANY_COL = "company";
    public static final String CUSTOMER_NAME_COL = "name";
    public static final String CUSTOMER_LASTNAME_COL = "lastname";

    private static final String CUSTOMERSTABLE_CREATESQL =
            "CREATE TABLE " + CUSTOMERSTABLE +
                    "(" +
                    CUSTOMER_ID_COL + " INTEGER PRIMARY KEY, " +
                    CUSTOMER_COMPANY_COL + " TEXT, " +
                    CUSTOMER_NAME_COL + " TEXT, " +
                    CUSTOMER_LASTNAME_COL + " TEXT " +
                    ")";
    public static final String ORDER_ID_COL = "_id";
    public static final String ORDER_CUSTOMERREF_COL = "customerid";
    public static final String ORDER_DATE_COL = "date";
    public static final String ORDER_DESTINATION_COL = "destination";

    private static final String ORDERSTABLE_SCREATSQL =
            "CREATE TABLE " + ORDERSTABLE +
                    "(" +
                    ORDER_ID_COL + " INTEGER PRIMARY KEY, " +
                    ORDER_CUSTOMERREF_COL + " INTEGER, " +
                    ORDER_DATE_COL + " LONG DEFAULT CURRENT_TIMESTAMP, " +
                    ORDER_DESTINATION_COL + " TEXT " +
                    ")";

    DBHelper(Context context) {
        super(context, DBNAME, null, DBVERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CUSTOMERSTABLE_CREATESQL);
        db.execSQL(ORDERSTABLE_SCREATSQL);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db,
                          int oldversion,
                          int newversion) {

    }

    public long insertCustomer(String company, String name, String lastname) {
        ContentValues cv = new ContentValues();
        cv.put(CUSTOMER_COMPANY_COL,company);
        cv.put(CUSTOMER_NAME_COL,name);
        cv.put(CUSTOMER_LASTNAME_COL,lastname);
        return this.getWritableDatabase().insert(CUSTOMERSTABLE,null,cv);
    }

    public long insertOrder(long customerid, String destination) {
        ContentValues cv = new ContentValues();
        cv.put(ORDER_CUSTOMERREF_COL,customerid);
        cv.put(ORDER_DESTINATION_COL,destination);
        return this.getWritableDatabase().insert(ORDERSTABLE,null,cv);
    }

    public Cursor getCustomers() {
        return this.getWritableDatabase().query(CUSTOMERSTABLE,
                null,null,null,null,null,null);
    }

    public Cursor getCustomerOrders(long customerref) {
        return this.getWritableDatabase().query(ORDERSTABLE,null,
                ORDER_CUSTOMERREF_COL+"=?",
                new String[]{Long.toString(customerref)},
                null,null,null);
    }
}

请注意，已使用适合自己的名称。这只是针对非常基本的功能进行了测试。

最初运行时显示： -

点击Compnay1会导致： -

我如何在ListViews上列出具有一对多关系的两个表

1 个答案:

工作示例

活动

DBHelper.java（SQLiteOpenHelper子类）