如何返回零使用COUNT（）與多個表

月 - month_id，月份名稱，....

獎 - award_id，獎勵名稱，.. ..

提名 - fk_award_id，fk_month_id，姓名，地址，...

我需要統計不同類型的每月頒發獎項的數量，而在病例返回0，其中沒有人授予

for ex。
結果應該看起來像

April-09  Gold   10 
April-09  Silver  2 
April-09  Bronze  0  
May-09  Gold   2 
May-09  Silver  1 
May-09  Bronze  0

這可能嗎？

來源

2009-10-19 Ron

一些數據來測試：

DECLARE @months TABLE 
(month_id INT IDENTITY, 
month_name VARCHAR(50) 
) 

INSERT INTO @months(month_name) VALUES ('April-09') 
INSERT INTO @months(month_name) VALUES ('May-09') 

DECLARE @awards TABLE 
(award_id INT IDENTITY, 
award_name VARCHAR(50) 
) 

INSERT INTO @awards(award_name) VALUES ('Bronze') 
INSERT INTO @awards(award_name) VALUES ('Silver') 
INSERT INTO @awards(award_name) VALUES ('Gold') 

DECLARE @nominations TABLE 
(fk_month_id INT, 
fk_award_id INT, 
other_field VARCHAR(10) 
) 

INSERT INTO @nominations(fk_month_id,fk_award_id,other_field) VALUES (1,1,'1') 
INSERT INTO @nominations(fk_month_id,fk_award_id,other_field) VALUES (1,1,'2') 
INSERT INTO @nominations(fk_month_id,fk_award_id,other_field) VALUES (2,2,'3') 
INSERT INTO @nominations(fk_month_id,fk_award_id,other_field) VALUES (2,1,'4') 
INSERT INTO @nominations(fk_month_id,fk_award_id,other_field) VALUES (3,1,'5') 
INSERT INTO @nominations(fk_month_id,fk_award_id,other_field) VALUES (3,2,'6') 
INSERT INTO @nominations(fk_month_id,fk_award_id,other_field) VALUES (3,2,'7')

和查詢

SELECT month_name, award_name, ISNULL(cnt,0) 
FROM @months 
CROSS JOIN @awards 
LEFT JOIN ( 
    SELECT fk_month_id,fk_award_id, COUNT(*) AS cnt 
    FROM @nominations 
    GROUP BY fk_month_id,fk_award_id 
) fk ON fk_month_id = month_id AND fk_award_id = award_id

結果是：

April-09 Bronze 2 
April-09 Silver 0 
April-09 Gold 0 
May-09 Bronze 1 
May-09 Silver 1 
May-09 Gold 0

來源

2009-10-19 19:50:53

group by month_id, award_id plus out join會做的伎倆

來源

2009-10-19 19:41:35

像這樣的東西是你所需要的。未經測試，但原則是：

SELECT m.Monthname, a.Awardname, COUNT(*) 
    FROM Month m 
     LEFT JOIN Nomination n ON n.fK_Month_ID = m.MonthID 
     LEFT JOIN Award a ON n.FK_Award_ID = a.AwardID 
    GROUP BY m.Monthname, a.Awardname

關鍵是GROUP BY條款。

來源

2009-10-19 19:48:37

如何返回零使用COUNT（）與多個表

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