Question

我想在我的程序中的两个日期之间显示年份和月份名称作为列名，如下所示

year    jan      Feb  ......Dec
----    -----   -----       -----
2016    val1       val2     val3
2017    val4       val5    val6

有人帮我做这个

Answer 1

如果我理解你正确地生成所需的结果集，你可以做这样的事情。 TIMESTAMPDIFF(DAY.... + INTERVAL 1 MONTH)可以计算一个月内的天数。请注意，每个TIMESTAMPDIFF(DAY, '2016-01-01', '2016-01-01' + INTERVAL 1 MONTH) AS 'Jan'行必须正好几个月，它应该有效。

<强>查询

SELECT 
   '2016' AS YEAR
 , TIMESTAMPDIFF(DAY, '2016-01-01', '2016-01-01' + INTERVAL 1 MONTH) AS 'Jan'
 , TIMESTAMPDIFF(DAY, '2016-02-01', '2016-02-01' + INTERVAL 1 MONTH) AS 'Feb'
 ...
 , TIMESTAMPDIFF(DAY, '2016-12-01', '2016-12-01' + INTERVAL 1 MONTH) AS 'Dec'

UNION ALL 

SELECT 
   '2017' AS YEAR
 , TIMESTAMPDIFF(DAY, '2017-01-01', '2017-01-01' + INTERVAL 1 MONTH) AS 'Jan'
 , TIMESTAMPDIFF(DAY, '2017-02-01', '2017-02-01' + INTERVAL 1 MONTH) AS 'Feb'
 ...
 , TIMESTAMPDIFF(DAY, '2017-12-01', '2017-12-01' + INTERVAL 1 MONTH) AS 'Dec'

<强>结果

year       Jan     Feb     Dec  
------  ------  ------  --------
2016        31      29        31
2017        31      28        31

或者这个查询使得添加新年和更少的代码重复变得更加容易。

<强>查询

SELECT 
   years.year
 , TIMESTAMPDIFF(DAY, CONCAT(years.year, '-01-01'), CONCAT(years.year, '-01-01') + INTERVAL 1 MONTH) AS 'Jan'
 , TIMESTAMPDIFF(DAY, CONCAT(years.year, '-02-01'), CONCAT(years.year, '-02-01') + INTERVAL 1 MONTH) AS 'Feb'
 ...
 , TIMESTAMPDIFF(DAY, CONCAT(years.year, '-12-01'), CONCAT(years.year, '-12-01') + INTERVAL 1 MONTH) AS 'Dec'
FROM ( 

  SELECT 
   '2016' AS YEAR

  UNION 
  ALL

  SELECT 
    '2017' AS YEAR
)
 AS years

<强>结果

year       Jan     Feb     Dec  
------  ------  ------  --------
2016        31      29        31
2017        31      28        31

在mysql中将月份名称显示为列名

1 个答案: