sql - 如何在 Group By 子句中使用聚合函数

Question

如何在这样的 GROUP BY 子句中使用聚合函数？

SELECT VCH_DCOA_CODE, SUM(VCH_DEFINATION.VCH_CREDIT) AS Debit
FROM  VCH_DEFINATION 
GROUP BY SUBSTRING(VCH_DCOA_CODE, 0, 6)

Answer 1

看起来你想显示sum()完整VCH_DCOA_CODE但group by子字符串值，所以我猜你想要这个：

SELECT v1.VCH_DCOA_CODE, v2.Debit
FROM VCH_DEFINATION v1
INNER JOIN
(
    select SUM(VCH_DEFINATION.VCH_CREDIT) AS Debit, SUBSTRING(VCH_DCOA_CODE, 0, 6) Shortcode
    from VCH_DEFINATION
    group by SUBSTRING(VCH_DCOA_CODE, 0, 6)
) v2
    on v1.SUBSTRING(VCH_DCOA_CODE, 0, 6) = v2.Shortcode

子查询将获得SUM()for eachSUBSTRING(VCH_DCOA_CODE, 0, 6)但随后将显示每个完整的VCH_DCOA_CODE

但是，如果您不想显示完整的VCH_DCOA_CODE，那么您可以使用内部查询来获取结果：

 select SUM(VCH_DEFINATION.VCH_CREDIT) AS Debit, SUBSTRING(VCH_DCOA_CODE, 0, 6) Shortcode
 from VCH_DEFINATION
 group by SUBSTRING(VCH_DCOA_CODE, 0, 6)

Answer 2

您必须添加SUBSTRING(VCH_DCOA_CODE, 0, 6)如下select条款：

SELECT SUBSTRING(VCH_DCOA_CODE, 0, 6), SUM(VCH_DEFINATION.VCH_CREDIT) AS Debit
FROM  VCH_DEFINATION 
GROUP BY SUBSTRING(VCH_DCOA_CODE, 0, 6)