在 mysql 中将月份名称显示为列名称

Question

我想在我的程序中的两个日期之间将年份和月份名称显示为列名称，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

如果我理解您正确提问以生成所需的结果集，您可以这样做。 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' 行中的月份必须是正确的，它应该有效。

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'

结果

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

或者此查询可以更轻松地添加新的一年并减少代码重复。

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

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称

display month names as column names in mysql

mysql

date

columnname