如何在按MONTH分组日期时将月份从INT转换为VARCHAR

Question

我需要以可读的方式总结这些年来每个月的采访次数。

SELECT month(i.Date) AS Month, Year(i.Date) AS Year, Count(i.Id) AS' Number of Interviews'
FROM Interviews i
GROUP BY month(i.Date), year(i.Date)
ORDER BY year(i.Date) DESC, month(Date) ASC

我希望查询返回Month作为VARCHAR，如'January'，而不是默认INT来自'month'函数。

Answer 1

对于MySql，它将是：

SELECT 
  monthname(i.Date) AS Month, 
  Year(i.Date) AS Year, 
  Count(i.Id) AS `Number of Interviews`
FROM Interviews i
GROUP BY month(i.Date), monthname(i.Date), year(i.Date)
ORDER BY year(i.Date) DESC, month(i.Date) ASC

对于SQL Server：

SELECT 
  datename(month, i.date) AS Month, 
  Year(i.Date) AS Year, 
  Count(i.Id) AS [Number of Interviews]
FROM Interviews i
GROUP BY month(i.Date), datename(month, i.date), year(i.Date)
ORDER BY year(i.Date) DESC, month(i.Date) ASC

Answer 2

适用于大多数DBMS的解​​决方案是CASE表达式。

SELECT CASE month(i.date)
         WHEN 1 THEN
           'January'
         ...
         WHEN 12 THEN
           'December'
       END month,
       year(i.date) year,
       count(i.id) number_of_interviews
       FROM interviews i
       GROUP BY month(i.date),
                year(i.date)
       ORDER BY year(i.date) DESC,
                month(i.date) ASC;

Answer 3

SELECT count（1），format（dateColumn，'yyyy-MM'）FROM tableName GROUP BY format（dateColumn，'yyyy-MM'）ORDER BY 2