Question

在谈到SQL Server时，我还是一个新手，在弄清楚如何创建函数时遇到了问题。

我正在尝试根据用户int输入进行选择。该输入将代替a.ID_Aluno = 8

上的数字8。

SELECT 
    a.ID_ALUNO, b.ID_ALUNO, b.ID_Registo, c.ID_Registo, c.Classificacao
FROM 
    Aluno a, Registo b, Avaliação c 
WHERE 
    a.ID_Aluno = 8 
    AND b.ID_Aluno = a.ID_Aluno 
    AND b.ID_Registo = c.ID_Registo

我需要用户提供此号码（本例中为8）

这是我的错误尝试：

ALTER FUNCTION CalculaMedia
    (@input INT)
RETURNS INT
AS 
BEGIN
    DECLARE @ALUNO INT
    DECLARE @MEDIA FLOAT

    SET @ALUNO = @input

    SET @MEDIA = (SELECT SUM(c.Classificacao * d.Valor_Componente) / COUNT(c.Classificacao)
                  FROM Aluno a, Registo b, Avaliação c, Componente d
                  WHERE a.ID_Aluno = @ALUNO 
                    AND b.ID_Aluno = a.ID_Aluno 
                    AND b.ID_Registo = c.ID_Registo 
                    AND c.ID_Componente = d.ID_Componente)

    RETURN @MEDIA 
END

Answer 1

如果您使用整数，则可能应该进行转换为浮点运算，以便除法为您提供更准确的结果。

SELECT 1.0 * SUM(c.Classificacao * d.Valor_Componente) / COUNT(c.Classificacao)

如何在SQL Server中的函数上进行选择

1 个答案: