在 SQLite 中生成平均值

Question

在我的应用程序中，我有 4 个活动，每个活动都与我的 SQLite 数据库中的一个表相关联。

1. 联赛 = 联赛
2. 保龄球桌 = 保龄球桌
3. 系列 = 系列表
4. 游戏 = 游戏桌

我正在尝试找出为每个系列生成平均分数的最佳方法。在将新游戏添加到系列之前，不会生成游戏 ID。

当投球手输入他/她的分数时，id 可能看起来像这样；

• 联赛 ID = 1
• 投球手 id = 3
• 系列 ID = 6
• 游戏 ID = 9,10,11

为系列 id 6 生成平均值的最佳解决方案是什么。我认为应该在每次输入分数并将其写入系列表中的平均值字段时生成平均值。有什么想法吗？

列出投球手比赛的方法：

public List<Game> getAllGames(String leagueId, String bowlerId, String seriesId) {
        List<Game> games = new ArrayList<>();

        //Select All Query
        String selectQuery = "SELECT  * FROM " + Game.TABLE_NAME + " WHERE " + Game.COLUMN_LEAGUE_ID + " = '" + leagueId + "'" + " AND " + Game.COLUMN_BOWLER_ID + " = '" + bowlerId + "'" + " AND " + Game.COLUMN_SERIES_ID + " = '" + seriesId + "'" + " ORDER BY " +
                Game.COLUMN_TIMESTAMP + " DESC";

        try (SQLiteDatabase db = this.getWritableDatabase()) {
            @SuppressLint("Recycle") Cursor cursor = db.rawQuery( selectQuery, null );

            //Looping Through All Rows And Adding To The List
            if (cursor.moveToFirst()) {
                do {
                    Game game1 = new Game();
                    game1.setId(cursor.getInt(cursor.getColumnIndex(Game.COLUMN_ID ) ) );
                    game1.setLeagueId(cursor.getString(cursor.getColumnIndex(Game.COLUMN_LEAGUE_ID)));
                    game1.setBowlerId(cursor.getString(cursor.getColumnIndex(Game.COLUMN_BOWLER_ID)));
                    game1.setSeriesId(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SERIES_ID)));
                    game1.setScore(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SCORE)));
                    game1.setStrikes(cursor.getString(cursor.getColumnIndex(Game.COLUMN_STRIKES)));
                    game1.setSpares(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SPARES)));
                    game1.setSplits(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SPLITS)));
                    game1.setSplitConversions(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SPLIT_CONVERSIONS)));
                    game1.setOpenFrames(cursor.getString(cursor.getColumnIndex(Game.COLUMN_OPEN_FRAMES)));
                    game1.setTimestamp(cursor.getString(cursor.getColumnIndex(Game.COLUMN_TIMESTAMP)));
                    games.add( game1 );
                } while (cursor.moveToNext());
            }

            //Close Database Connection
            db.close();
        }

        //Return Game List
        return games;
    }

我在想，既然我使用上面的代码列出了投球手的所有游戏，我可以在将它们加载到列表视图时将分数相加。我将如何去完成这样的事情？

数据库助手

public class DatabaseHelper extends SQLiteOpenHelper {

    //Database Version
    private static final int DATABASE_VERSION = 1;

    //Database Name
    private static final String DATABASE_NAME = "tpc_database";


    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    //Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {

        db.execSQL(League.CREATE_TABLE);
        db.execSQL(Bowler.CREATE_TABLE);
        db.execSQL(Series.CREATE_TABLE);
        db.execSQL(Game.CREATE_TABLE);

    }



    //Upgrade Database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        //Drop Older Table If It Existed
        db.execSQL("DROP TABLE IF EXISTS " + League.TABLE_NAME);
        db.execSQL("DROP TABLE IF EXISTS " + Bowler.TABLE_NAME);
        db.execSQL("DROP TABLE IF EXISTS " + Series.TABLE_NAME);
        db.execSQL("DROP TABLE IF EXISTS " + Game.TABLE_NAME);


        //Create Tables Again
        onCreate( db );
    }

    //************************                ************************
    //************************ League Methods ************************
    //************************                ************************

    public long insertLeague(String leagueName) {
        //Get Writable Database That We Want To Write Data Too
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();

        //`id` and `timestamp` Will Be Inserted Aromatically
        values.put(League.COLUMN_NAME, leagueName);

        //Insert Row
        long id = db.insert(League.TABLE_NAME, null, values);

        //Close Database Connection
        db.close();

        //Return Newly Inserted Row Id
        return id;
    }

    public League getLeague(long id) {
        //Get Readable Database If We Are Not Inserting Anything
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query(League.TABLE_NAME,
                new String[]{League.COLUMN_ID, League.COLUMN_NAME, League.COLUMN_TIMESTAMP},
                League.COLUMN_ID + "=?",
                new String[]{String.valueOf(id)}, null, null, null, null);

        if (cursor.moveToFirst()) {

            //Prepare League Object
            League league = new League(
                    cursor.getInt(cursor.getColumnIndex(League.COLUMN_ID)),
                    cursor.getString(cursor.getColumnIndex(League.COLUMN_NAME)),
                    cursor.getString(cursor.getColumnIndex(League.COLUMN_TIMESTAMP)));

            //Close Database Connection
            cursor.close();
            return league;
        } else {
            return null;
        }
    }

    public List<League> getAllLeagues() {
        List<League> leagues = new ArrayList<>();

        //Select All Query
        String selectQuery = "SELECT  * FROM " + League.TABLE_NAME + " ORDER BY " +
                League.COLUMN_TIMESTAMP + " DESC";

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        //Looping Through All Rows And Adding To The List
        if (cursor.moveToFirst()) {
            do {
                League league = new League();
                league.setId(cursor.getInt(cursor.getColumnIndex(League.COLUMN_ID)));
                league.setName(cursor.getString(cursor.getColumnIndex(League.COLUMN_NAME)));
                league.setTimestamp(cursor.getString(cursor.getColumnIndex(League.COLUMN_TIMESTAMP)));

                leagues.add(league);
            } while (cursor.moveToNext());
        }
        cursor.close();
        //Close Database Connection
        db.close();

        //Return League List
        return leagues;
    }

    public int getLeaguesCount() {
        String countQuery = "SELECT  * FROM " + League.TABLE_NAME;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);

        int count = cursor.getCount();
        cursor.close();

        //Return The Count
        return count;
    }

    public int updateLeague(League league) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put( League.COLUMN_NAME, league.getName() );

        //Updating Row
        return db.update(League.TABLE_NAME, values, League.COLUMN_ID + " = ?",
                new String[]{String.valueOf(league.getId())});
    }

    public void deleteLeague(League league) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(League.TABLE_NAME, League.COLUMN_ID + " = ?",
                new String[]{String.valueOf( league.getId())});
        db.close();
    }

    //************************                ************************
    //************************ Bowler Methods ************************
    //************************                ************************

    public long insertBowler(String leagueId, String bowlerName) {
        //Get Writable Database That We Want To Write Data Too
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();

        //`id` and `timestamp` Will Be Inserted Automatically
        values.put(Bowler.COLUMN_LEAGUE_ID, leagueId);
        values.put(Bowler.COLUMN_NAME, bowlerName);

        //Insert Row
        //long id = db.insert(Bowler.TABLE_NAME, null, values);
        long id = db.insertOrThrow( Bowler.TABLE_NAME, null, values );
        Log.d("INSERTBOWLER","Number of bowlers in db = " + String.valueOf( DatabaseUtils.queryNumEntries(db,Bowler.TABLE_NAME)));
        //Close Database Connection
        db.close();

        //Return Newly Inserted Row Id
        return id;
    }

    public Bowler getBowler(String leagueId) {
        //Get Readable Database If We Are Not Inserting Anything
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query( Bowler.TABLE_NAME,
                new String[]{Bowler.COLUMN_ID, Bowler.COLUMN_LEAGUE_ID, Bowler.COLUMN_NAME, Bowler.COLUMN_TIMESTAMP},
                Bowler.COLUMN_LEAGUE_ID + "=?",
                new String[]{String.valueOf(leagueId)}, null, null, null, null);

        Bowler bowler = null;
        if (cursor.moveToFirst()) {

            //Prepare Bowler Object
            bowler = new Bowler(
                    cursor.getInt(cursor.getColumnIndex(Bowler.COLUMN_ID)),
                    cursor.getString(cursor.getColumnIndex(Bowler.COLUMN_LEAGUE_ID)),
                    cursor.getString(cursor.getColumnIndex(Bowler.COLUMN_NAME)),
                    cursor.getString(cursor.getColumnIndex(Bowler.COLUMN_TIMESTAMP)));

            //Close Database Connection
            cursor.close();
            return bowler;
        } else {
            return bowler;
        }
    }
    public List<Bowler> getAllBowlers(String leagueId) {
        List<Bowler> bowlers = new ArrayList<>();

        //Select All Query
        String selectQuery = "SELECT  * FROM " + Bowler.TABLE_NAME + " WHERE " + Bowler.COLUMN_LEAGUE_ID + " = '" + leagueId + "'" + " ORDER BY " +
                Bowler.COLUMN_TIMESTAMP + " DESC";

        Log.d("GETALLBOWLERS-SQL","SQL used = >>>>" +selectQuery + "<<<<");

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        Log.d("GETALLBOWLERS-CNT","Number of rows retrieved = " + String.valueOf(cursor.getCount()));


        //Looping Through All Rows And Adding To The List
        if (cursor.moveToFirst()) {
            do {
                Bowler bowler = new Bowler();
                bowler.setId(cursor.getInt(cursor.getColumnIndex(Bowler.COLUMN_ID)));
                bowler.setLeagueId(cursor.getString(cursor.getColumnIndex(Bowler.COLUMN_LEAGUE_ID)));
                bowler.setName(cursor.getString(cursor.getColumnIndex(Bowler.COLUMN_NAME)));
                bowler.setTimestamp(cursor.getString(cursor.getColumnIndex(Bowler.COLUMN_TIMESTAMP)));
                bowlers.add(bowler);
            } while (cursor.moveToNext());
        }
        cursor.close();
        //Close Database Connection
        db.close();
        Log.d("GETALLBOWLERS-CNT","Number of elements in bowlerslist = " + String.valueOf(bowlers.size()));

        //Return Bowlers List
        return bowlers;
    }

    public int getBowlersCount() {
        String countQuery = "SELECT  * FROM " + Bowler.TABLE_NAME;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);

        int count = cursor.getCount();
        cursor.close();

        //Return The Count
        return count;
    }

    public int updateBowler(Bowler bowler) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(Bowler.COLUMN_LEAGUE_ID, bowler.getLeagueId());
        values.put(Bowler.COLUMN_NAME, bowler.getName());

        //Updating Row
        return db.update(Bowler.TABLE_NAME, values, Bowler.COLUMN_ID + " = ?",
                new String[]{String.valueOf(bowler.getId())});
    }

    public void deleteBowler(Bowler bowler) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete( Bowler.TABLE_NAME, Bowler.COLUMN_ID + " = ?",
                new String[]{String.valueOf( bowler.getId())});
        db.close();
    }

    //************************                ************************
    //************************ Series Methods ************************
    //************************                ************************

    public long insertSeries(String leagueId, String bowlerId, String seriesName) {

        //Get Writable Database That We Want To Write Data Too
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        //`id` and `timestamp` Will Be Inserted Automatically
        values.put(Series.COLUMN_LEAGUE_ID, leagueId);
        values.put(Series.COLUMN_BOWLER_ID, bowlerId);
        values.put(Series.COLUMN_NAME, seriesName);


        //Insert Row
        //long id = db.insert( Series.TABLE_NAME, null, values );
        long id = db.insertOrThrow( Series.TABLE_NAME, null, values );
        Log.d("INSERT SERIES","Number of series in db = " + String.valueOf( DatabaseUtils.queryNumEntries(db,Series.TABLE_NAME)));

        //Close Database Connection
        db.close();

        //Return Newly Inserted Row Id
        return id;
    }

    public Series getSeries(String leagueId, String bowlerId) {
        //Get Readable Database If We Are Not Inserting Anything
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query( Series.TABLE_NAME,
                new String[]{Series.COLUMN_ID, Series.COLUMN_LEAGUE_ID, Series.COLUMN_BOWLER_ID,
                        Series.COLUMN_NAME, Series.COLUMN_SERIES_AVERAGE, Series.COLUMN_TIMESTAMP},
                Series.COLUMN_LEAGUE_ID + "=?" + " AND " +  Series.COLUMN_BOWLER_ID + "=?",
                new String[]{String.valueOf(leagueId), String.valueOf(bowlerId)}, null, null, null, null);

        if (cursor.moveToFirst()) {

            //Prepare Series Object
            Series series = new Series(
                    cursor.getInt(cursor.getColumnIndex(Series.COLUMN_ID)),
                    cursor.getString(cursor.getColumnIndex(Series.COLUMN_LEAGUE_ID)),
                    cursor.getString(cursor.getColumnIndex(Series.COLUMN_BOWLER_ID)),
                    cursor.getString(cursor.getColumnIndex(Series.COLUMN_NAME)),
                    cursor.getString(cursor.getColumnIndex(Series.COLUMN_SERIES_AVERAGE)),
                    cursor.getString(cursor.getColumnIndex(Series.COLUMN_TIMESTAMP)));

            //Close Database Connection
            cursor.close();
            return series;
        } else {
            return null;
        }
    }

    public List<Series> getAllSeries(String leagueId, String bowlerId) {
        List<Series> series = new ArrayList<>();

        //Select All Query
        String selectQuery = "SELECT * FROM " + Series.TABLE_NAME + " WHERE " + Series.COLUMN_LEAGUE_ID + " = '" + leagueId + "'" + " AND " + Series.COLUMN_BOWLER_ID + " = '" + bowlerId + "'"+ " ORDER BY " +
                Series.COLUMN_TIMESTAMP + " DESC";

        Log.d("GET ALL SERIES-SQL","SQL used = >>>>" +selectQuery + "<<<<");

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        Log.d("GET ALL SERIESS-CNT","Number of rows retrieved = " + String.valueOf(cursor.getCount()));

        //Looping Through All Rows And Adding To The List
        if (cursor.moveToFirst()) {
            do {
                Series series1 = new Series();
                series1.setId(cursor.getInt(cursor.getColumnIndex(Series.COLUMN_ID)));
                series1.setLeagueId(cursor.getString(cursor.getColumnIndex(Series.COLUMN_LEAGUE_ID)));
                series1.setBowlerId(cursor.getString(cursor.getColumnIndex(Series.COLUMN_BOWLER_ID)));
                series1.setName(cursor.getString(cursor.getColumnIndex(Series.COLUMN_NAME)));
                series1.setAverage(cursor.getString(cursor.getColumnIndex(Series.COLUMN_SERIES_AVERAGE)));
                series1.setTimestamp(cursor.getString(cursor.getColumnIndex(Series.COLUMN_TIMESTAMP)));
                series.add(series1);
            } while (cursor.moveToNext());
        }
        cursor.close();
        //Close Database Connection
        db.close();
        Log.d("GETALLSERIES-CNT","Number of elements in serieslist = " + String.valueOf(series.size()));
        //Return Series List
        return series;
    }

    public int getSeriesCount() {
        String countQuery = "SELECT  * FROM " + Series.TABLE_NAME;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery( countQuery, null );

        int count = cursor.getCount();
        cursor.close();

        //Return The Count
        return count;
    }

    public int updateSeries(Series series) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(Series.COLUMN_LEAGUE_ID, series.getLeagueId());
        values.put(Series.COLUMN_BOWLER_ID, series.getBowlerId());
        values.put(Series.COLUMN_NAME, series.getName());
        values.put(Series.COLUMN_SERIES_AVERAGE,series.getAverage());

        //Updating Row
        return db.update( Series.TABLE_NAME, values, Series.COLUMN_ID + " = ?",
                new String[]{String.valueOf( series.getId() )} );

    }

    public void deleteSeries(Series series) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete( Series.TABLE_NAME, Series.COLUMN_ID + " = ?",
                new String[]{String.valueOf( series.getId() )} );
        db.close();
    }

    //************************                ************************
    //************************  Game Methods  ************************
    //************************                ************************

    public long insertGame(String leagueId, String bowlerId, String seriesId, String score, String strikes, String spares, String splits, String splitConversions, String openFrames) {

        //Get Writable Database That We Want To Write Data Too
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        //`id` and `timestamp` Will Be Inserted Automatically
        values.put(Game.COLUMN_LEAGUE_ID, leagueId);
        values.put(Game.COLUMN_BOWLER_ID, bowlerId);
        values.put(Game.COLUMN_SERIES_ID, seriesId);
        values.put(Game.COLUMN_SCORE, score);
        values.put(Game.COLUMN_STRIKES, strikes);
        values.put(Game.COLUMN_SPARES, spares);
        values.put(Game.COLUMN_SPLITS, splits);
        values.put(Game.COLUMN_SPLIT_CONVERSIONS, splitConversions);
        values.put(Game.COLUMN_OPEN_FRAMES, openFrames);

        //Insert Row
        long id = db.insert( Game.TABLE_NAME, null, values );

        //Close Database Connection
        db.close();

        //Return Newly Inserted Row Id
        return id;
    }

    public Game getGame(String leagueId, String bowlerId, String seriesId) {
        //Get Readable Database If We Are Not Inserting Anything
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query( Game.TABLE_NAME,
                new String[]{Game.COLUMN_ID, Game.COLUMN_LEAGUE_ID, Game.COLUMN_BOWLER_ID,
                        Game.COLUMN_SERIES_ID, Game.COLUMN_SCORE, Game.COLUMN_STRIKES, Game.COLUMN_SPARES, Game.COLUMN_SPLITS, Game.COLUMN_SPLIT_CONVERSIONS, Game.COLUMN_OPEN_FRAMES, Game.COLUMN_TIMESTAMP},
                Game.COLUMN_LEAGUE_ID + "=?" + " AND " + Game.COLUMN_BOWLER_ID + "=?" + " AND " + Game.COLUMN_SERIES_ID + "=?",
                new String[]{String.valueOf( leagueId ), String.valueOf( bowlerId ), String.valueOf( seriesId )}, null, null, null, null );

        if (cursor.moveToFirst()) {

            //Prepare Game Object
            Game game = new Game(
                    cursor.getInt( cursor.getColumnIndex(Game.COLUMN_ID)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_LEAGUE_ID)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_BOWLER_ID)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_SERIES_ID)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_SCORE)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_STRIKES)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_SPARES)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_SPLITS)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_SPLIT_CONVERSIONS)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_OPEN_FRAMES)),
                    cursor.getString( cursor.getColumnIndex(Game.COLUMN_TIMESTAMP)));

            //Close Database Connection
            cursor.close();
            return game;
        } else {
            return null;
        }
    }

    public List<Game> getAllGames(String leagueId, String bowlerId, String seriesId) {
        List<Game> games = new ArrayList<>();

        //Select All Query
        String selectQuery = "SELECT  * FROM " + Game.TABLE_NAME + " WHERE " + Game.COLUMN_LEAGUE_ID + " = '" + leagueId + "'" + " AND " + Game.COLUMN_BOWLER_ID + " = '" + bowlerId + "'" + " AND " + Game.COLUMN_SERIES_ID + " = '" + seriesId + "'" + " ORDER BY " +
                Game.COLUMN_TIMESTAMP + " DESC";

        try (SQLiteDatabase db = this.getWritableDatabase()) {
            @SuppressLint("Recycle") Cursor cursor = db.rawQuery( selectQuery, null );

            //Looping Through All Rows And Adding To The List
            if (cursor.moveToFirst()) {
                do {
                    Game game1 = new Game();
                    game1.setId(cursor.getInt(cursor.getColumnIndex(Game.COLUMN_ID ) ) );
                    game1.setLeagueId(cursor.getString(cursor.getColumnIndex(Game.COLUMN_LEAGUE_ID)));
                    game1.setBowlerId(cursor.getString(cursor.getColumnIndex(Game.COLUMN_BOWLER_ID)));
                    game1.setSeriesId(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SERIES_ID)));
                    game1.setScore(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SCORE)));
                    game1.setStrikes(cursor.getString(cursor.getColumnIndex(Game.COLUMN_STRIKES)));
                    game1.setSpares(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SPARES)));
                    game1.setSplits(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SPLITS)));
                    game1.setSplitConversions(cursor.getString(cursor.getColumnIndex(Game.COLUMN_SPLIT_CONVERSIONS)));
                    game1.setOpenFrames(cursor.getString(cursor.getColumnIndex(Game.COLUMN_OPEN_FRAMES)));
                    game1.setTimestamp(cursor.getString(cursor.getColumnIndex(Game.COLUMN_TIMESTAMP)));
                    games.add( game1 );
                } while (cursor.moveToNext());
            }

            //Close Database Connection
            db.close();
        }

        //Return Game List
        return games;
    }

    public int getGameCount() {
        String countQuery = "SELECT  * FROM " + Game.TABLE_NAME;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery( countQuery, null );

        int count = cursor.getCount();
        cursor.close();

        //Return The Count
        return count;
    }

    public int updateGame(Game game) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(Game.COLUMN_LEAGUE_ID, game.getLeagueId());
        values.put(Game.COLUMN_BOWLER_ID, game.getBowlerId());
        values.put(Game.COLUMN_SERIES_ID, game.getSeriesId());
        values.put(Game.COLUMN_SCORE, game.getScore());
        values.put(Game.COLUMN_STRIKES, game.getStrikes());
        values.put(Game.COLUMN_SPARES, game.getSpares());
        values.put(Game.COLUMN_SPLITS, game.getSplits());
        values.put(Game.COLUMN_SPLIT_CONVERSIONS, game.getSplitConversions());
        values.put(Game.COLUMN_OPEN_FRAMES, game.getOpenFrames());

        //Updating Row
        return db.update( Game.TABLE_NAME, values, Game.COLUMN_ID + " = ?",
                new String[]{String.valueOf( game.getId() )} );

    }

    public void deleteGame(Game game) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(Game.TABLE_NAME, Game.COLUMN_ID + " = ?",
                new String[]{String.valueOf( game.getId() )} );
        db.close();
    }
}

Answer 1

sqlite> create table test (a int);
sqlite> insert into test values (1);
sqlite> insert into test values (2);
sqlite> insert into test values (3);
sqlite> insert into test values (4);
sqlite> select avg(a) as average, count(a) as count, sum(a) as sum from test;
average     count       sum       
----------  ----------  ----------
2.5         4           10        
sqlite> select avg(a) as average, count(a) as count, sum(a) as sum from test
  where a > 2;
average     count       sum       
----------  ----------  ----------
3.5         2           7

Answer 2

我真的不明白你想要什么，但如果你想获得表格中所有列的平均值，请执行以下操作：

1 添加所有系列 ID。 （添加：将所有值放入一个数组并使用array_sum()）

2 使用mysqli_num_rows() 并计算表中的所有行数

如何取平均值：

将所有数字相加，然后除以有多少个数字。换句话说，它是总和除以计数。

3 将数组总和除以所有行数。