Question

我正在创建一个应用，用户可以登录到自己的帐户，通过EditText中的内容，然后它会显示在TextView中。我的观点是保存并显示每个用户自己的文本。这是我到目前为止所得到的

public class DatabaseHelper extends SQLiteOpenHelper {
    // Database Version
    private static final int DATABASE_VERSION = 3;

    // Database Name
    private static final String DATABASE_NAME = "UserManager.db";

    // User table name
    private static final String TABLE_USER = "user";

    // User Table Columns names
    private static final String COLUMN_USER_ID = "userid";
    private static final String COLUMN_USER_NAME = "user_name";
    private static final String COLUMN_USER_PASSWORD = "user_password";
    private static final String COLUMN_USER_HOURS = "user_hours";

    // create table sql query
    private String CREATE_USER_TABLE = "CREATE TABLE " + TABLE_USER + "("
            + COLUMN_USER_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + COLUMN_USER_NAME + " TEXT,"
            + COLUMN_USER_PASSWORD + " TEXT," + COLUMN_USER_HOURS + " TEXT" + ")";

    // drop table sql query
    private String DROP_USER_TABLE = "DROP TABLE IF EXISTS " + TABLE_USER;
    SQLiteDatabase db;


    /**
     * Constructor
     *
     * @param context
     */
    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 3);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        this.db = sqLiteDatabase;
        db.execSQL(CREATE_USER_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        //Drop User Table if exist
        db.execSQL(DROP_USER_TABLE);
        // Create tables again
        onCreate(db);

    }

    public void addUser(User user) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(COLUMN_USER_NAME, user.getName());
        values.put(COLUMN_USER_PASSWORD, user.getPassword());

        // Inserting Row
        db.insert(TABLE_USER, null, values);
        db.close();
    }

    public boolean checkUser(String name, String password) {

        // array of columns to fetch
        String[] columns = {
                COLUMN_USER_ID
        };
        SQLiteDatabase db = this.getReadableDatabase();
        // selection criteria
        String selection = COLUMN_USER_NAME + " = ?" + " AND " + COLUMN_USER_PASSWORD + " = ?";

        // selection arguments
        String[] selectionArgs = {name, password};

        Cursor cursor = db.query(TABLE_USER, //Table to query
                columns,                    //columns to return
                selection,                  //columns for the WHERE clause
                selectionArgs,              //The values for the WHERE clause
                null,                       //group the rows
                null,                       //filter by row groups
                null);                      //The sort order

        int cursorCount = cursor.getCount();

        cursor.close();
        db.close();
        if (cursorCount > 0) {
            return true;
        }

        return false;
    }

    public void updateData(UserData userData) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(COLUMN_USER_HOURS, userData.getHours() );

        // updating row
        db.update(TABLE_USER, values, COLUMN_USER_HOURS + " = ?",
                new String[]{String.valueOf(userData.getHours())});
        db.close();
    }

我想要从列COLUMN_USER_HOUR存储和检索用户的EditText值，遗憾的是我不知道如何将它们全部设置在一起，我假设应该为每个用户的ID识别COLUMN_USER_HOUR。感谢帮助 ;）这是UserData

public class UserData {
    private String hours;

    public String getHours(){
        return hours;
    }

    public void setHours(String hours){
        this.hours = hours;}

}

Answer 1

您可以将upDateData方法更改为： -

public int updateData(long userid, UserData userData) {
    int rv;
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(COLUMN_USER_HOURS, userData.getHours() );

    // updating row
    rv = db.update(TABLE_USER, values, COLUMN_USER_ID + " = ?",
            new String[]{Long.toString(userid)});
    db.close();
    return rv;
}

因此，您传递 userid 以及要更改的数据，该方法将返回所做的更新次数（如果有效则为1，如果没有更新则为0）。

回答： -

我知道，但是现在我只想知道如何保存和检索唯一用户的数据（当用户登录我想要的帐户时）在textview中显示他通过edittext存储在数据中的内容i 知道这听起来很奇怪，但我试图了解如何构建数据：）

类似的更改，而不是返回布尔值返回用户ID（如果失败则返回0），例如： -

public long checkUser(String name, String password) {
    long rv = 0;

    // array of columns to fetch
    String[] columns = {
            COLUMN_USER_ID
    };
    SQLiteDatabase db = this.getReadableDatabase();
    // selection criteria
    String selection = COLUMN_USER_NAME + " = ?" + " AND " + COLUMN_USER_PASSWORD + " = ?";

    // selection arguments
    String[] selectionArgs = {name, password};

    Cursor cursor = db.query(TABLE_USER, //Table to query
            columns,                    //columns to return
            selection,                  //columns for the WHERE clause
            selectionArgs,              //The values for the WHERE clause
            null,                       //group the rows
            null,                       //filter by row groups
            null);                      //The sort order

    if (cursor.moveToFirst) {
        rv = Long.toString(cursor.getLong(csr.getColumnIndex(COLUMN_USER_ID);
    }

    cursor.close();
    db.close();
    return rv;
}

你可以使用getHours方法： -

public String getHours(long id) {
    String rv = "";
    SQLiteDatabase db = this.getWriteableDatabase();
    Cursor cursor = db.query(TABLE_USER, 
        null,
        COLUMN_USER_ID = "+?",
        new String[]{Long.toString(id)},
        null,null,null
    );
    if (cursor.moveToFirst()) {
        rv = cursor.getString(cursor.getColumnIndex(COLUMN_USER_HOURS));
    }
    cursor.close();
    db.close();
    return rv;
}

您的活动可能包含以下内容： -

    DatabaseHelper dbhlpr = new DatabaseHelper(this);
    long current_userid = dbhlpr.checkUser(
            username_EditText.getText().toString(),
            userpassword_EditText.gettext.toString());
    if (current_userid > 0) {
        hours_TextView.settext(dbhlpr.getHours(current_userid));
    } else {
        //.... handle invalid login attempt here.
    }

如何在SQLite中保存和检索特定行的数据？

1 个答案:

回答： -