Question

我有一个＆＃39;吸引力的数据库表＆＃39;每个景点都有县和/或城市的列。我需要按字母顺序显示县和城市的列表，以及每个县或城市的记录总数。

以下SQL查询工作正常，但COUNT显示每个只有一个，而不是每个县或城市的景点总数。

有人能告诉我如何将下面两个SQL语句组合在一起吗？

SQL：

   SELECT entry, COUNT(entry) AS totalForEntry 
   FROM ( SELECT DISTINCT county AS entry
          FROM venues 
          WHERE (county  IS NOT NULL AND county <> '' ) 

          UNION ALL 

          SELECT DISTINCT city as entry
          FROM venues
          WHERE (city IS NOT NULL 
                 AND
                 city  <> ''  
                 )
      ) X GROUP BY entry ORDER BY entry ASC

结果：

Hove (1)
Inverness-shire (1)
Isle of Man (1)
Kent (1)
Lancashire (1)
Leeds (1)
Leicester (1)
Leicestershire (2)
Lincolnshire (1)
Liverpool (1)

以下有关计算县的工作，我需要它来统计城市并将其与上述查询相结合：

SELECT DISTINCT county, COUNT(county) AS Count
FROM venues
WHERE (county IS NOT NULL AND county <> '') 
GROUP BY county ORDER BY county ASC

正确的结果应该是：

Hove (7)
Inverness-shire (3)
Isle of Man (12)
Kent (20)
Lancashire (34)
Leeds (31)
Leicester (5)
Leicestershire (53)
Lincolnshire (7)
Liverpool (43)

非常感谢提前。

Answer 1

将DISTINCT与GROUP BY一起使用是没有意义的。你可以这样做：

SELECT county AS entry, COUNT(county) AS Count
FROM venues
WHERE (county IS NOT NULL AND county <> '') 
GROUP BY county 

UNION ALL 

SELECT city as entry, COUNT(city) As Count
FROM venues
WHERE (city IS NOT NULL AND city  <> '')
GROUP BY city 
ORDER BY entry ASC

在MySQL中使用Distinct，Count和Group

1 个答案: