计算我的SQL中2列的百分比

Question

我试图在SQL中获得两列的百分比，但是由于某种原因，方程的除法部分没有发生？

我对此很陌生，但很高兴学习。谢谢您的帮助！

SELECT      
    Jaar,
    SUM(Bedrag) AS 'Totaal te innen contributie',
    (SELECT SUM(Bedrag) 
     FROM Betaling 
     WHERE Jaar = Contributie.Jaar) AS 'Totaal geïnde contributie',
    CAST((SUM(Bedrag) / (SELECT SUM(Bedrag) 
                         FROM Betaling 
                         WHERE Jaar = Contributie.Jaar) * 100) AS numeric(7,2)) AS 'percentage beta' 
FROM    
    Contributie 
GROUP BY    
    Jaar

Answer 1

我们可以使用联接来实现：

SELECT      
    c.Jaar,
    SUM(c.Bedrag) AS 'Totaal te innen contributie',
    b.bedrag_sum AS 'Totaal geïnde contributie',
    100.0 * SUM(c.Bedrag) / b.bedrag_sum AS 'percentage beta'
FROM Contributie c
LEFT JOIN
(
    SELECT Jaar, SUM(Bedrag) AS bedrag_sum
    FROM Betaling
    GROUP BY Jaar
) b
    ON c.Jaar = b.Jaar
GROUP BY
    c.Jaar;

别名为b的子查询将替换您在select子句中拥有的相关子查询。