从两个sql查询中减去多行

Question

我创建了一个投注数据库，我正在尝试确定谁是最好的和最差的。我决定这样做的最简单方法是获取用户的奖金总和，然后减去他们下注的总金额

我的第一个 SQL 查询是

SELECT fromuser,SUM(itemsgiven::int)
FROM transactions
WHERE transtype='Bet Placed'
GROUP BY fromuser
ORDER BY 2 DESC

返回这个

fromuser    sum
15228328    2689
13896406    2634
55954103    308
37460340    64
66589399    62

那么我的第二个查询是确定总奖金

SELECT touser,SUM(itemsgiven::float)
FROM transactions
WHERE transtype='Bet Won'
GROUP BY touser
ORDER BY 2 DESC

返回这个

touser      sum
15228328    4387.515
55954103    152.295
13896406    120.285
66589399    71.28
37460340    56.925

我的问题是结合这些查询的最佳方式是什么，这样我就可以有两列，一列是用户 ID，另一列是他们的总赢（或输）。我查找了一些示例，但让我感到困惑的部分是，您如何确保在减去仅从同一用户 ID 中减去的两个总和时。

编辑：我正在使用 postgresql

Answer 1

你可以使用这个查询：

SELECT usr, SUM(subtotal) AS total
FROM (
  SELECT   fromuser AS usr, SUM(itemsgiven::int) AS subtotal
  FROM     transactions
  WHERE    transtype='Bet Placed'
  GROUP BY fromuser

  UNION ALL

  SELECT   touser AS usr, -1*SUM(itemsgiven::float) AS subtotal
  FROM     transactions
  WHERE    transtype='Bet Won'
  GROUP BY touser
) s
GROUP BY usr
ORDER BY 2 DESC

您确定 itemsgiven::int 和 itemsgiven::float 吗？

Answer 2

你可以用UNION做到这一点：

 SELECT user_id, SUM(itemsgiven) as total_itemsgiven
 FROM
 (
   SELECT fromuser user_id, - itemsgiven::int itemsgiven
   FROM transactions
   WHERE 'Bet Placed' 
   UNION
   SELECT touser user_id, itemsgiven::int itemsgiven
   FROM transactions
   WHERE 'Bet Won'

 ) t
 GROUP BY user_id 
 ORDER BY 2 DESC

Answer 3

你可以使用 UNION

SELECT * FROM 
(SELECT fromuser as a,SUM(itemsgiven::numeric) as b
FROM transactions
WHERE transtype='Bet Placed'
GROUP BY fromuser
UNION 
SELECT touser as a,SUM(itemsgiven::numeric) as b
FROM transactions
WHERE transtype='Bet Won'
GROUP BY touser
) c
ORDER BY c.b DESC