MySQL GROUP BY - 获取该特定组中的项目答案

【问题标题】：MySQL GROUP BY - get items in that particular groupMySQL GROUP BY - 获取该特定组中的项目
【发布时间】：2009-07-02 14:06:53
【问题描述】：

我正在使用 MySQL GROUP BY 函数，想知道是否有一种方法可以在无需再次查询的情况下获取该组的项目数？

$homePointsPlayerResult = mysql_query("SELECT `player_id` FROM `conversions` WHERE `game_id` = '$game_id' AND `team_id` IS NULL GROUP BY `player_id`");

while ($players_with_points_conversions[] = mysql_fetch_row($homePointsPlayerResult)) {
    if (array_search($players_with_points_conversions['player_id'],$home_players,true) == FALSE) {
        $home_players['player_id'] = $players_with_points_conversions['player_id'];
        $home_players['conversions'] = {WANT NUMBER OF ELEMENTS FOR THIS GROUP};
    }
}

非常感谢您的回答。提前致谢。

【问题讨论】：

标签： php mysql

【解决方案1】：

您可以获取COUNT：

SELECT `player_id`, COUNT(*) AS conversions FROM `conversions` WHERE `game_id` = '$game_id' AND `team_id` IS NULL GROUP BY `player_id`

【讨论】：

【解决方案2】：

只需在 SELECT 列表中添加另一列，如下所示：“count(player_id) AS elementCount”

【讨论】：