計數記錄問題

這可能是一個簡單的，但我不能讓我的頭靠近它。計數記錄問題

我有MemberBusinessCats的表，它包含一個BusinessCatID和MEMBERID ..表可以提出這樣的：

+-----------------------+-----------------+------------+ 
| MemberBusinessCatID | BusinessCatID | MemberID | 
+-----------------------+-----------------+------------+ 
| 27     | 45    | 102  | 
+-----------------------+-----------------+------------+ 
| 28     | 55    | 102  | 
+-----------------------+-----------------+------------+ 
| 29     | 61    | 102  | 
+-----------------------+-----------------+------------+ 
| 30     | 45    | 33  | 
+-----------------------+-----------------+------------+ 
| 31     | 23    | 33  | 
+-----------------------+-----------------+------------+ 
| 32     | 45    | 73  | 
+-----------------------+-----------------+------------+ 
| 32     | 61    | 73  | 
+-----------------------+-----------------+------------+ 
| 32     | 45    | 73  | 
+-----------------------+-----------------+------------+

如何使一個腳本來顯示下列數據

+-----------------+---------------------+ 
| BusinessCatID | NumMembers In Cat | 
+-----------------+---------------------+ 
| 45    | 3     | 
+-----------------+---------------------+ 
| 55    | 1     | 
+-----------------+---------------------+ 
| 61    | 2     | 
+-----------------+---------------------+ 
| 23    | 1     | 
+-----------------+---------------------+

非常感謝提前。

neojakey

來源

2013-02-20 neojakey

試試這個

select BusinessCatID ,count(BusinessCatID) as NumMembers_In_Cat 
    from MemberBusinessCats 
    group by BusinessCatID

DEMO SQLFIDDLE

來源

2013-02-20 17:45:25

您需要使用聚合函數與GROUP BY：

select BusinessCatID, count(*) NumMembersInCat 
from MemberBusinessCats 
group by BusinessCatID

見SQL Fiddle with Demo

這也可以使用count() over()寫：

select distinct BusinessCatID, 
    count(*) over(partition by BusinessCatID) NumMembersInCat 
from MemberBusinessCats

見SQL Fiddle with Demo

如果要計算每種類別中成員的數量，那麼你可以使用：

select BusinessCatID, 
    count(distinct MemberID) NumMembersInCat 
from MemberBusinessCats 
group by BusinessCatID

見SQL Fiddle with Demo

來源

2013-02-20 17:45:34 Taryn

試試這個

select BusinessCatID, COUNT(BusinessCatID) 
from MemberBusinessCatID 
group by BusinessCatID

來源

2013-02-20 17:47:35 EProgrammerNotFound

試試這個（或像這樣）：

 select BusinessCatID ,count(*) as NumMembersInCat 
     from MemberBusinessCats 
     group by BusinessCatID

來源

2013-02-20 17:48:17 Joe

Select BusinessCatID, count(MemberID) as [NumMembers In Cat] 
from MemberBusinessCats 
group by BusinessCatID, MemberID

來源

2013-02-20 17:48:42

我不你認爲你想用'memberID'進行分組 - 請參閱前面的4個答案... – 2013-02-20 17:58:51

基於這樣的事實，你有一個組合BusinessCatID & MEMBERID被列出了兩次，但只算（45,73）一旦你需要做一個COUNT（DISTINCT x）的

SELECT BusinessCatID, COUNT(DISTINCT MemberID) as NumMembersInCat 
FROM MemberBusinessCatID 
GROUP BY BusinessCatID

這將計算每BusinessCatID獨特成員（基於MEMBERID）。如果你不擔心dups，那麼使用COUNT（MemberID）或者COUNT（1）就可以正常工作。

來源

2013-02-20 17:58:34

以上答案中的非答案給出了他*所需*的期望輸出。他接受了錯誤的答案。每個人都很親密，但你比任何人都更親近。我認爲它應該是'Count（Distinct MemberBusinessCatID）' – Kaf 2013-02-20 18:09:15

實際上，我的確給出了正確的答案，而不是順序。 Count（Distinct MemberBusinessCatID）給出了相同的答案。該操作並沒有真正指定他想要的方式。儘管簡單的改變。 – 2013-02-20 18:17:59

我明白這個問題來自不同的TRIPLE（MemberBusinessCATID，BusinessCATID，MemberID），總和爲BusinessCATID。在這種情況下看不同三元組或雙打是相同的，但在較大的數據集可能有差異：

創建的視圖：

create view dist_catView as 
SELECT distinct MemberBusinessCATID, BusinessCATID, Member ID from cat_table

然後

SELECT BusinessCATID, count(MemberID) from dist_catView 
group by BusinessCATID

來源

2013-02-20 19:37:15

計數記錄問題

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