按日期选择多列，为每列

-2

SELECT `Num_1`, COUNT(`Num_1`) AS `value_occurrence` FROM numbers WHERE MONTH(`Dates`) = 1 AND YEAR(`Dates`) = 1995 GROUP BY `Num_1` ORDER BY `value_occurrence` DESC

，但对于多列，在“NUM_1”，“NUM_2”，“Num_3”，' Num_4'，'Num_5'并且返回每个列的出现，诸如'num_1_occurrence'，'num_2_occurrence'，'num_3_occurrence'，'num_4_occurrence'，'num_5_occurrence'以及全部在指定日期内。

numbers table Example output

使用我试过......

SELECT `Num_1`,`Num_2`, `Num_3`,`Num_4`,`Num_5`,COUNT(`Num_1`,`Num_2`,`Num_3`,`Num_4`,`Num_5`) AS `num_1_occurrence`,`num_2_occurrence`,`num_3_occurrence`, `num_4_occurrence`,`num_5_occurrence`FROM numbers WHERE MONTH(`Dates`) = 1 AND YEAR(`Dates`) = 1995

，但只是把错误，我已经广泛地搜索了天，还没有找到正确的方法来做到这一点。

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2016-10-27 Jerry Guthrie

添加示例数据和预期输出 –

更新后的表格和示例输出图像，输出就像我想要的，但需要它的所有列 –

我会做这样的：

SELECT n.num 
    , MAX(IF(n.q='n1',n.cnt,NULL)) AS num_1_occurrence 
    , MAX(IF(n.q='n2',n.cnt,NULL)) AS num_2_occurrence 
    , MAX(IF(n.q='n3',n.cnt,NULL)) AS num_3_occurrence 
    FROM (
     SELECT 'n1'   AS q 
       , n1.Num_1  AS num 
       , COUNT(n1.Num_1) AS cnt 
      FROM numbers n1 
      WHERE n1.Dates >= '1995-01-01' 
      AND n1.Dates < '1995-01-01' + INTERVAL 1 MONTH 
      GROUP BY n1.Num_1 

      UNION ALL 

     SELECT 'n2'   AS q 
       , n2.Num_2  AS num 
       , COUNT(n2.Num_2) AS cnt 
      FROM numbers n2 
      WHERE n2.Dates >= '1995-01-01' 
      AND n2.Dates < '1995-01-01' + INTERVAL 1 MONTH 
      GROUP BY n2.Num_2 

      UNION ALL 

     SELECT 'n3'   AS q 
       , n3.Num_3  AS num 
       , COUNT(n3.Num_3) AS cnt 
      FROM numbers n3 
      WHERE n3.Dates >= '1995-01-01' 
      AND n3.Dates < '1995-01-01' + INTERVAL 1 MONTH 
      GROUP BY n3.Num_3 
     ) n 
GROUP BY n.num 
ORDER BY GREATEST(num_1_occurrence,num_2_occurrence,num_3_occurrence) DESC

来源

2016-10-27 22:56:51 spencer7593

我只是做NUM_1和NUM_2这里，但我认为这是你要找的东西，或关闭。这将为您提供“高”格式的列表，其中包含原始列名称，该列中的值以及该列中该值的计数...

SELECT 'Num_1' AS field_name, Num_1 AS value, value_count 
FROM (SELECT Num_1, COUNT(Num_1) AS value_count 
     FROM numbers 
     GROUP BY Num_1) AS num1_counts 
WHERE MONTH(`Dates`) = 1 AND YEAR(`Dates`) = 1995 

UNION 

SELECT 'Num_2' AS field_name, Num_2 AS value, value_count 
FROM (SELECT Num_2, COUNT(Num_2) AS value_count 
     FROM numbers 
     GROUP BY Num_2) AS num2_counts 
WHERE MONTH(`Dates`) = 1 AND YEAR(`Dates`) = 1995

来源

2016-10-27 23:59:36

按日期选择多列，为每列

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