SQL Server AVG和Excel AVERAGE产生不同的结果？

Question

我想在SQL服务器上显示平均值，但是当我在Excel中测试数据时结果不一样，必须有一些明显的我缺少的东西。

下面是从SQL Server的代码和结果：

SELECT DISTINCT 
d.d_reference + ' - ' + d.d_name AS Faculty, 
AVG(sub.GroupSize) AS FacultyAverage 


FROM 
unitesnapshot.dbo.capd_register r 
INNER JOIN unitesnapshot.dbo.capd_studentregister sr ON sr.sr_register = r.r_id 
INNER JOIN unitesnapshot.dbo.capd_activity a ON a.a_register = r.r_id 
INNER JOIN unitesnapshot.dbo.capd_moduleactivity ma ON ma.ma_activity = a.a_id 
INNER JOIN unitesnapshot.dbo.capd_module m ON m.m_id = ma.ma_activitymodule 
INNER JOIN unitesnapshot.dbo.capd_department d ON d.d_id = m.m_moduledept 
INNER JOIN unitesnapshot.dbo.capd_section sec ON sec.s_id = m.m_modulesection 
INNER JOIN (SELECT 
      r.r_reference, 
      COUNT(DISTINCT s.s_studentreference) AS GroupSize 
      FROM 
      unitesnapshot.dbo.capd_student s 
      INNER JOIN unitesnapshot.dbo.capd_person p ON p.p_id = s.s_id 
      INNER JOIN unitesnapshot.dbo.capd_studentregister sr ON sr.sr_student = p.p_id 
      INNER JOIN unitesnapshot.dbo.capd_register r ON r.r_id = sr.sr_register 
      GROUP BY 
      r.r_reference) sub ON sub.r_reference = r.r_reference 

WHERE 
SUBSTRING(r.r_reference,4,2) = '12' AND 
d.d_reference = '730' 

GROUP BY 
d.d_reference, 
d.d_name 

这是效果在Excel中：

感谢

Answer 1

尝试此好玩：

select avg(a) 
from 
    (values(1),(2),(3),(4)) x(a); 

avg(a) 
------- 
2 

AVG（）返回与基列相同的数据类型。如果您的列的类型为int，那么结果也会被截断为int。以下返回“正确”的结果。

select avg(cast(a as decimal(10,5))) 
from 
    (values(1),(2),(3),(4)) x(a); 

result 
-------- 
2.5 

你呈现的差异（24 VS 19.50484）将最有可能涉及与此相伴随的另一个错误。例如，要检查您是否在Excel中总结了与SQL Server中相同的数据，请将此结果转储到Excel中并对其进行总结。如果它与您目前认为的SQL Server数据的Excel 等效的不匹配，请将列对齐并检查它们是否具有相同的行数。然后按值ASCENDING分别对每列进行排序并再次比较。

SELECT d.d_name, sub.GroupSize AS FacultyAverage 
FROM unitesnapshot.dbo.capd_register r 
INNER JOIN unitesnapshot.dbo.capd_studentregister sr ON sr.sr_register = r.r_id 
INNER JOIN unitesnapshot.dbo.capd_activity a ON a.a_register = r.r_id 
INNER JOIN unitesnapshot.dbo.capd_moduleactivity ma ON ma.ma_activity = a.a_id 
INNER JOIN unitesnapshot.dbo.capd_module m ON m.m_id = ma.ma_activitymodule 
INNER JOIN unitesnapshot.dbo.capd_department d ON d.d_id = m.m_moduledept 
INNER JOIN unitesnapshot.dbo.capd_section sec ON sec.s_id = m.m_modulesection 
INNER JOIN (SELECT r.r_reference, 
      COUNT(DISTINCT s.s_studentreference) AS GroupSize 
      FROM unitesnapshot.dbo.capd_student s 
      INNER JOIN unitesnapshot.dbo.capd_person p ON p.p_id = s.s_id 
      INNER JOIN unitesnapshot.dbo.capd_studentregister sr ON sr.sr_student = p.p_id 
      INNER JOIN unitesnapshot.dbo.capd_register r ON r.r_id = sr.sr_register 
      GROUP BY r.r_reference) sub ON sub.r_reference = r.r_reference 
WHERE SUBSTRING(r.r_reference,4,2) = '12' AND d.d_reference = '730' 
ORDER BY d.d_name