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我的数据库保留前 10 条记录。db为空时，db记录分数，一路正确插入，直到有10条记录。然后，例如，当 db 有 10 个分数，并且用户得到一个应该是新的 #1 分数的分数时，它只是用新的分数替换当前的 #1 分数，而不是插入并将其下方的所有内容向下颠倒一个并且删除最低分数。希望我解释得很好，但如果不只是评论，我会尝试进一步澄清。

我的问题是我怎样才能让高分正确执行，因为当高分已经满了 10 条记录时，一条新记录被插入到正确的位置，而它下面的其余部分全部向下移动，最后一条记录得到完全撞倒了（因为它是新的#11）。

数据库助手.java

public class DatabaseHelper extends SQLiteOpenHelper { 

    SQLiteDatabase db;

    private static final int DATABASE_VERSION = 6; 
    private static final String DB_NAME = "test3"; 
    private static final String DB_PATH = "/data/data/matt.lyons.bibletrivia/databases/";
    private static final String TABLE = "HighscoresList"; 

    // Table columns names. 
    private static final String RANK = "_id"; 
    private static final String SCORE = "score"; 
    private static final String PERCENTAGE = "percentage";
    private static final String TOTAL_SCORE = "total_score";
    private static final String CATEGORY = "category";

    //Constructor for a DatabaseHelper.
    public DatabaseHelper(Context context) { 
        super(context, DB_NAME, null, DATABASE_VERSION); 
    }

    //Open the DB so it is editable.
    public SQLiteDatabase openDB() {
        db = this.getWritableDatabase();
        return db;
    }

    //Delete a selected one row.
    public void delete(long lowScore) {
        lowScore = getLowest();
        db.delete(TABLE, TOTAL_SCORE + "=" + lowScore, null);
    }

    //Sort rows in order of the TOTAL_SCORE column.
    public long getLowest() {
        Cursor c = db.rawQuery("SELECT * FROM " + TABLE + " ORDER BY " + TOTAL_SCORE, null);
        long count = c.getCount();
        long lowScore = -1;
        if(count == 10) {
            c.moveToLast();
            lowScore = c.getInt(c.getColumnIndex(TOTAL_SCORE));
        }
        return lowScore;
    }

    //Calculate the TOTAL_SCORE based on the SCORE and PERCENTAGE of a game.
    public long calculateTotalScore(long score, int percentage) {
        long i;
        return i = (percentage * 1000) + score;
    }

    //Check if new record makes the top 10.
    public long check(long score, int percentage, long sum) {
        Cursor c = db.rawQuery("SELECT " + TOTAL_SCORE + " FROM " + TABLE, null);
        long count = c.getCount();
        long low_score;
        if(count == 10) {
            c.moveToLast();
            low_score = c.getInt(c.getColumnIndex(TOTAL_SCORE));
            return low_score;
        } else {
            return count;
        }
    }

    //Insert new record.
    public long insert(long score, int percentage, long total_score, String category) {
        ContentValues values = new ContentValues();
        values.put(SCORE, score);
        values.put(PERCENTAGE, percentage);
        values.put(TOTAL_SCORE, total_score);
        values.put(CATEGORY, category);

        return db.insert(TABLE, null, values);
    }

    //Create the table and all columns.
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + TABLE + " ("
                + RANK + " INTEGER PRIMARY KEY AUTOINCREMENT,"
                + SCORE + " LONG,"
                + PERCENTAGE + " INTEGER,"
                + CATEGORY + " STRING,"
                + TOTAL_SCORE + " LONG"
                + ");");
    }
}

结果.java

public class Results extends Activity {

    DatabaseHelper dh;

    public void onCreate(Bundle savedInstanceState) {

        dh = new DatabaseHelper(this);
        dh.openDB();
        showResults();
    }

    public void showResults() {

        total_score = dh.calculateTotalScore(score, percentage);
        if(dh.getLowest() == -1) {
            dh.insert(score, percentage, total_score, category);
        } else {
            dh.delete(dh.getLowest());
            dh.insert(score, percentage, total_score, category);
        }
    }
}
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1 回答 1

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为什么不只是：

"SELECT LIMIT 10 * FROM " + TABLE + " ORDER BY TOTAL_SCORE DESC"

这样你就可以得到前十名而不必一直插入/删除？

于 2013-02-18T15:48:53.913 回答