在我的应用程序中，我有4个活动，每个活动都与SQLite数据库中的一个表相关联。
我正在尝试找出为每个系列赛产生平均分数的最佳方法。在将新游戏添加到系列中之前，不会生成游戏ID。
当投球手输入分数时，id可能看起来像这样；
为Series ID 6生成平均值的最佳解决方案是什么。我在想，每次输入分数并将其写入Series表的平均值字段时，均应生成平均值。有什么想法吗？
列出礼帽游戏的方法：
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;
}
我一直在想，由于我使用上述代码列出了一个保龄球馆的所有比赛，因此我可以在将得分加载到列表视图中时将得分相加。我将如何完成这样的事情？
DatabaseHelper
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();
}
}
答案 0 :(得分：0)
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
答案 1 :(得分：0)
我无法真正理解您想要的内容，但是如果要获取表中所有列的平均值，则可以执行以下操作：
1添加所有系列ID。 （要添加：将所有值放入数组中并使用array_sum()）
2使用mysqli_num_rows()并计算表中的所有行
如何获取平均值：
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Array总和除以所有行数。