Question

- 编辑 - 解决方案 -

感谢laalto我意识到我忘记更新我的DataSource中的allColumns数组，以在我的SQL查询中显示我的新列：

private String[] allColumns = {ClientDataSQLHelper.COLUMN_ID, ClientDataSQLHelper.COLUMN_CLIENT_NAME,
                        ClientDataSQLHelper.COLUMN_CLIENT_ADDRESS, ClientDataSQLHelper.COLUMN_CLIENT_NUMBER,
                        ClientDataSQLHelper.COLUMN_EMPLOYEE_ID};

- 初始问题 -

所以我试图在Android上创建一个简单的数据库，它将维护客户名称，地址和数字，以及为与客户合作的员工附加员工ID（想想清洁或家庭护理服务）。我遇到的问题是我的表应该（从我认为我的设计方式）应该有5行，给定以下SQL查询字符串：

private static final String DB_CREATE = "create table " + TABLE_CLIENTS + "(" +
        COLUMN_ID + " integer primary key autoincrement, " +
        COLUMN_EMPLOYEE_ID + " integer, " +
        COLUMN_CLIENT_NAME + " text not null, " +
        COLUMN_CLIENT_ADDRESS + " text not null, " +
        COLUMN_CLIENT_NUMBER + " text not null);";

在我的SQLHelper类中，以及各自的变量：

public static final String TABLE_CLIENTS = "clients";
public static final String COLUMN_ID = "_id"; 
public static final String COLUMN_CLIENT_NAME = "name";
public static final String COLUMN_CLIENT_ADDRESS = "address";
public static final String COLUMN_CLIENT_NUMBER = "number";
public static final String COLUMN_EMPLOYEE_ID = "employee_id";

此查询在我的SQLHelper的Overriden SQL查询中执行：

@Override
public void onCreate(SQLiteDatabase db) {
    Log.d(TAG, "creating database");
    db.execSQL(DB_CREATE);
}

我遇到的问题是，当我尝试实现我的DataSource类时，我的getAllClients（）方法：

public List <ClientHolder> getAllClients(){
    List<ClientHolder> clients = new ArrayList<ClientHolder>();

    // Again, without our Cursor, we can't actually point at any of the data we want to
    // work with/manipulate
    Cursor cursor = db.query(SQLHelper.TABLE_CLIENTS, allColumns, 
            null, null, null, null, null);
    cursor.moveToFirst();

    while(!cursor.isAfterLast()){
        ClientHolder client = cursorToClient(cursor);
        clients.add(client);
        cursor.moveToNext();
    }

    cursor.close();
    if(clients.size() == 0){
        return null;
    }
    return clients;
}

利用我的cursorToClient（）方法从我的数据库中的光标位置实际获取数据：

private ClientHolder cursorToClient(Cursor cursor){
    ClientHolder client = new ClientHolder();
    long id = cursor.getLong(0);
    String name = cursor.getString(1);
    String address = cursor.getString(2);
    String number = cursor.getString(3);

    Log.d(TAG, "Client " + id + ": " + name + ", " + address + ", " + number);

    int employeeId = cursor.getInt(4);  // THIS IS MY ERROR LINE

    client.setClientID(id);
    client.setClientName(name);
    client.setClientAddress(address);
    client.setClientNumber(number);
    client.setEmployeeID(employeeId);
    return client;
}

在线上整数employeeId = cursor.getInt（4）;我收到错误Failed to read row 0, column 4 from a CursorWindow which has 1 rows, 4 columns.但是根据我的SQL创建查询（_id，name，address，number，employee_id）我应该有5列，不是吗？我的日志打印正确，所以到目前为止我的值是正确的，似乎我的SQL的COLUMN_EMPLOYEE_ID + " integer, "部分没有被有效地实现。

Answer 1

可能是以下任何一种情况：

您allColumns投影只有4列。
您编辑了表架构，忘记更新数据库文件。请参阅When is SQLiteOpenHelper onCreate() / onUpgrade() run?

您的更新问题显示原因是1。

简单的SQLite数据库获取Cursor错误

1 个答案: