Android：外键（希望每辆车都有自己的记录保存在SQLite中）

Question

我的android应用程序是关于汽车管理的。我将有汽车清单及其管理，如（燃料、旅行、维修）。假设我在列表中有 2 辆车 i) 本田 ABC 123。 ii) 丰田 ABC 298.

我应该怎么做才能将特定汽车的记录存储在table（燃料，行驶，维修）中？我在燃料、旅行和修理 table 辆汽车 table 中尝试了外键。但是外键的值为空。我不知道该怎么办。

这是我的数据库汽车Table

     /*
     * ====================================================================
     * TABLE CAR COLUMNS
     * ====================================================================
     */
    public static final String TABLE_CAR = "car";
    public static final String COLUMN_CAR_ID = "_id";
    public static final String COLUMN_CAR_NAME = "car_name";

 * ====================================================================
 * CREATING CAR TABLE
 * ====================================================================

public static final String DATABASE_CREATE_TABLE_CAR = "create table "
        + TABLE_CAR + "(" + COLUMN_CAR_ID + " integer primary key autoincrement, "
        + COLUMN_CAR_NAME + " text );";

这里是修复table

 * ====================================================================
 * TABLE REPAIR COLUMNS
 * ====================================================================

public static final String TABLE_REPAIR = "repair";
public static final String COLUMN_REPAIR_ID = "_id";
public static final String COLUMN_REPAIR_DATE = "repair_date";
public static final String COLUMN_REPAIR_TYPE = "repair_type";
public static final String COLUMN_REPAIR_TOTAL_COST = "repair_total_cost";
public static final String COLUMN_REPAIR_LOCATION = "repair_location";
public static final String COLUMN_REPAIR_DETAILS = "repair_details";
public static final String COLUMN_REPAIR_CAR_ID = "car_id";


 * ====================================================================
 * CREATING REPAIR TABLE
 * ====================================================================

public static final String DATABASE_CREATE_TABLE_REPAIR = "create table "
        + TABLE_REPAIR + "(" + COLUMN_REPAIR_ID
        + " integer primary key autoincrement, " + COLUMN_REPAIR_DATE
        + " text, " + COLUMN_REPAIR_TYPE + " text not null, "
        + COLUMN_REPAIR_TOTAL_COST + " number, " + COLUMN_REPAIR_DETAILS
        + " text not null, " + COLUMN_REPAIR_LOCATION + " text not null, " + COLUMN_REPAIR_CAR_ID
        + " integer, "  +
            "FOREIGN KEY (car_id) REFERENCES car(_id)" + " ON DELETE CASCADE );";

这是我的主屏幕，我从那里 select 一辆车

这是我的修复屏幕这是维修清单（显示两辆车的维修数据，我想要我select）

的车的数据

我得到外键 (car_id) 为空。

Answer 1

你应该使用 ORMLite。使用外键非常容易，您无需编写任何 sql 查询。 link for ormlite. Here is instruction to use (but in Russian)

Android：外键（希望每辆车都有自己的记录保存在SQLite中）

Android: Foreign Key (want every car have its own record to be save in SQLite)

android

sqlite

foreign-keys