在SQL中計數

Question

AFDELING = DEPARTMENT。 MEDLEM = MEMBER。我想查看每個部門的成員數量，顯示部門名稱，但我似乎無法使其工作。我得到的只是Personnr的重複。使用

SELECT AFDELING.afdnavn, MEDLEM.personnr, count(*) 
FROM [dbo].[MEDLEM],[dbo].AFDELING 
WHERE AFDELING.afdnr = MEDLEM.afdnr 
GROUP BY AFDELING.afdnavn, MEDLEM.personnr 
GO 

表：

 
AFDELING 
Afdnr (Primary Key) 
Afdnavn 

 
MEDLEM 
Afdnr (foreign key) 
Personnr (foreign key) (Primary key) 

Answer 1

SELECT 
    AFDELING.afdnavn 
    , COUNT(MEDLEM.personnr) 
FROM 
    dbo.AFDELING JOIN 
    dbo.MEDLEM ON AFDELING.afdnr = MEDLEM.afdnr 
GROUP BY 
    AFDELING.afdnavn 

Answer 2

我覺得你的錯誤是，你被MEDLEM.personnr分組。你只能通過AFDELING.afdnavn需要組，做count

select 
    A.afdnavn, 
    count(*) as number 
from dbo.AFDELING as A 
    inner join dbo.MEDLEM as M on M.afdnr = A.afdnr 
group by A.afdnavn