sql将两列相加并将两者相加答案

【问题标题】：sql sum two columns and add up bothsql将两列相加并将两者相加
【发布时间】：2019-01-25 07:48:44
【问题描述】：

我有一个包含多个乒乓球比赛得分的数据库。要进行排名，我需要计算多列。

我想将独特的回合相加，以了解人们参与的频率。我还想把所有获胜的游戏加起来。有时我们会玩“超级回合”（SR），获胜的游戏会翻倍。 SR 默认设置为 1。

要知道总分，我想将两个结果（参与和总游戏数）相加。

我现在拥有的：

$sql_user = $conn->query("
SELECT user_id, count(distinct round) as participation, 
sum(IFNULL(GAMES_WIN,0) * SR) AS total_games 
FROM tt_game group by user_id ORDER BY user_id ASC");

是否可以这样做：

$sql_user = $conn->query("
SELECT user_id, count(distinct round) as participation, 
sum(IFNULL(GAMES_WIN,0) * SR) AS total_games 
sum(participation + total_games) AS total_score
FROM tt_game group by user_id ORDER BY total_score DESC");

我如何回应这些结果？非常感谢！

【问题讨论】：

标签： php select mysqli count sum

【解决方案1】：

不，您不能在 SELECT 子句本身中引用在 SELECT 子句中定义的别名。

您可以重复表达式：

SELECT
  user_id,
  count(distinct round) as participation, 
  sum(IFNULL(GAMES_WIN,0) * SR) AS total_games, 
  count(distinct round) + sum(IFNULL(GAMES_WIN,0) * SR) AS total_score
FROM tt_game 
GROUP BY user_id
ORDER BY total_score DESC;

或者使用子查询：

SELECT user_id, participation, total_games, participation + total_game AS total_score
FROM
(
  SELECT
    user_id,
    count(distinct round) as participation, 
    sum(IFNULL(GAMES_WIN,0) * SR) AS total_games
  FROM tt_game 
  GROUP BY user_id
) aggregated
ORDER BY total_score DESC;

【讨论】：

【解决方案2】：

另一个选择呢？

我认为您需要另一个选择，在其中计算 total_score。

试试这样的：

$sql_user = $conn->query("
SELECT t.user_id, t.participation, t.total_games, (participation + total_games) AS total_score
FROM (SELECT user_id, count(distinct round) as participation, sum(IFNULL(GAMES_WIN, 0) * SR) AS total_games
      FROM tt_game
      group by user_id
      ORDER BY total_score DESC) AS t
");

【讨论】：