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我有以下查询

SELECT (CASE WHEN cc.country IS NULL THEN dc.country ELSE cc.country END) AS Country,l.band FROM lotw l
 OUTER LEFT JOIN CountryCode cc on cc.code = l.dxcc
 OUTER LEFT JOIN DeleteCountry dc on dc.code = l.dxcc
 WHERE l.DXCC > ''  GROUP BY cc.Country,dc.country

产生以下结果

Country                     Band

Bonaire                     15M
St. Maarten                 40M
Aland Is.                   20M
Alaska                      15M
Andorra                     80M
Antigua & Barbuda           10M
Argentina                   10M 
Aruba                       10M
Ascension Is.               20M
Asiatic Russia              40M
Austral I.                  40M

…………</p>

我需要得到的是每个乐队的计数？

  Band         Total
  10M           50 
  20M           20
  30M            5

所以我尝试了这个：

   select Band,Count(Band) FROM( 
     SELECT (CASE WHEN cc.country IS NULL THEN dc.country ELSE cc.country END) AS Country,
     l.band FROM lotw l
     OUTER LEFT JOIN CountryCode cc on cc.code = l.dxcc
     OUTER LEFT JOIN DeleteCountry dc on dc.code = l.dxcc
     WHERE l.DXCC > ''  GROUP BY cc.Country,dc.country
    )group by Band

这几乎奏效了，但计数已关闭，例如 10M，计数应为 79，而它的计数为 27？

但是，如果我使用此查询并将其限制为 10M 它可以工作，但我只能得到一个波段：

select Band,Count(Band) FROM( 
 SELECT (CASE WHEN cc.country IS NULL THEN dc.country ELSE cc.country END) AS Country,
 l.band FROM lotw l
 OUTER LEFT JOIN CountryCode cc on cc.code = l.dxcc
 OUTER LEFT JOIN DeleteCountry dc on dc.code = l.dxcc
 WHERE l.DXCC > '' AND BAND = '10M' GROUP BY cc.Country,dc.country
)

不知道该怎么做。

4

1 回答 1

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您将不得不使用 COUNT(*) 语句。以下应该适用于计数列：

SELECT Band, COUNT(*) AS Total 
FROM lotw l 
OUTER LEFT JOIN CountryCode cc ON cc.code = l.dxcc 
OUTER LEFT JOIN DeleteCountry dc ON dc.code = l.dxcc
WHERE l.DXCC > '' 
GROUP BY l.band

这是使用 Count() 的链接：http: //www.w3schools.com/sql/sql_func_count.asp

于 2013-07-10T22:46:00.183 回答