Question

我使用此代码将User对象保存到SQLite中，但是我收到此错误。什么问题和解决方案？

日志

11-12 13:48:18.647: E/AndroidRuntime(2409): Caused by: android.database.sqlite.SQLiteException:               no such column: firstname (code 1): , 
while compiling: SELECT id, firstname, lastname, phonenumber, groupname FROM Users WHERE  id = ?

代码

MySQLiteHelper sql=new MySQLiteHelper(MainActivity.this, "users");
for(int i=0;i<5;i++)
sql.addUser(new User());

for(int i=1;i<=5;i++)
    Log.i(i+"", sql.getUser(i).toString());

/////////////////////////////////////////////// ////////////////////////////////////////////////// ////////////////////////////////////////////////// ///////////////////////////

public class MySQLiteHelper extends SQLiteOpenHelper {

    // Database Version
    private static final int DATABASE_VERSION = 2;
    // Database Name
    private static String TABLE_NAME = "Users";

    public static String DB_NAME;
    public static String DB_PATH;
    private Context myContext;
    SQLiteDatabase db1;




    public MySQLiteHelper(Context context,String Databasename) {
        super(context, Databasename, null, DATABASE_VERSION); 
        myContext=context;

    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // SQL statement to create User table
        String CREATE_User_TABLE = "CREATE TABLE " + TABLE_NAME + " (id " +
                "INTEGER PRIMARY KEY AUTOINCREMENT, firstname TEXT,lastname TEXT,phonenumber TEXT,groupname TEXT)";

        // create Users table
        db.execSQL(CREATE_User_TABLE);
    }


    // Users table name

    // Users Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_FIRSTNAME = "firstname";
    private static final String KEY_LASTNAME = "lastname";
    private static final String KEY_PHONENUMBER = "phonenumber";
    private static final String KEY_GROUPNAME = "groupname";

    private static final String[] COLUMNS = {KEY_ID,KEY_FIRSTNAME,KEY_LASTNAME,KEY_PHONENUMBER,KEY_GROUPNAME};


    public void addUser(User user){

        // 1. get reference to writable DB
        SQLiteDatabase db = this.getWritableDatabase();

        // 2. create ContentValues to add key "column"/value
        ContentValues values = new ContentValues();

 values.put(KEY_FIRSTNAME, user.getFirstName());
 values.put(KEY_LASTNAME, user.getLastName());
 values.put(KEY_PHONENUMBER, user.getPhoneNumber());
 values.put(KEY_GROUPNAME, user.getGroupName());
        // 3. insert
        db.insert(TABLE_NAME, // table
                null, //nullColumnHack
                values); // key/value -> keys = column names/ values = column values

        // 4. close
        db.close();
    }

    public User getUser(int id){

        // 1. get reference to readable DB
        SQLiteDatabase db = null ;

        db = this.getReadableDatabase();

        // 2. build query
        Cursor cursor =
                db.query(TABLE_NAME, // a. table
                COLUMNS, // b. column names
                " id = ?", // c. selections
                new String[] { String.valueOf(id) }, // d. selections args
                null, // e. group by
                null, // f. having
                null, // g. order by
                null); // h. limit

        // 3. if we got results get the first one
        if (cursor != null)
            cursor.moveToFirst();

        System.gc();
        // 4. build User object
        User user=new User();
        user.setId(Integer.parseInt(cursor.getString(0)));
        user.setFirstname(cursor.getString(1));
        user.setLastname(cursor.getString(2));
        user.setPhoneNumber(cursor.getString(3));
        user.setGroupName(cursor.getString(4));

        cursor.close();
        return user;
    }




     @Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Drop older Users table if existed
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);

    // create fresh Users table
    this.onCreate(db);
}





    @Override
    public synchronized void close() {
        if(db1!=null)db1.close();
        //super.close();

    }


}

Answer 1

我怀疑你的问题是你之前没有得到更新的表的迭代。我看到您使用的是版本2.您需要在onUpgrade函数中提供更新说明，否则请吹掉数据库并重试。如果没有任何重要信息，我建议清除程序存储器，其中包括所有数据库，并查看它是否有效。

编辑：你的onUpgrade工作正常，但我怀疑你的代码中有一些迭代。您可以增加版本，或按照我上面的建议进行操作。

在android中插入SQLite数据库时出错

1 个答案: