sqlite - SQLite：获取两个日期之间的平均工作日

Question

我有一个Trucks带有两个日期列的表：Arrival和Released. 我可以计算这些日期之间的平均天数，如下所示：

SELECT avg(julianday(released) - julianday(arrival)) 
FROM Trucks

但是，我只想计算工作日——也就是说，我想忽略周六和周日。有没有办法在 SQLite 中做到这一点？我见过更健壮的 RDBMS 的解决方案，如 Oracle 和 MSSQL，但没有一个适用于 SQLite。

Answer 1

天数的原始差异必须（仅）根据arrival和released天的星期几进行调整：

rel arr|0 1 2 3 4 5 6
-------+-+-+-+-+-+-+-
  0    |2 0 0 0 0 0 1
  1    |2 2 0 0 0 0 1
  2    |2 2 2 0 0 0 1
  3    |2 2 2 2 0 0 1
  4    |2 2 2 2 2 0 1
  5    |2 2 2 2 2 2 1
  6    |2 2 2 2 2 2 2

这个数字可以用一个简单的表达式来计算（这里：内部 CASE 表达式）：

SELECT
AVG(julianday(released) - julianday(arrival) -
    CASE WHEN julianday(released) = julianday(arrival) THEN 0
    ELSE (CAST((julianday(released) - julianday(arrival)) / 7 AS INTEGER) * 2
         ) +
      CASE WHEN strftime('%w', arrival) <= strftime('%w', released) THEN 2
           ELSE strftime('%w', arrival) = '6'
      END
    END)
FROM trucks

（类似x='6'返回 0 或 1 的布尔表达式。）

Answer 2

好的，我想出了一个使用大量嵌套CASE语句的非常混乱的解决方案。它检查工作日编号，released然后检查工作日编号，arrival并计算已过去多少周。之后，我添加 0、1 或 2 作为这两天之间必须经过的周末天数的基数（即从周五到周一始终是 +2 个周末天，即使在这两天之间经过的时间还不到一整周）日期）。

在这里，以防有人发现它有用。很可能是我写过的最丑陋的 SQL。如果有人想出更好的方法，请告诉我。

（根据 CL 的反馈为简单起见进行了编辑）

SELECT 
avg(
julianday(released) - julianday(arrival) - 

CASE WHEN julianday(released) = julianday(arrival) THEN 0 ELSE
CASE strftime('%w', released) 
WHEN '0' THEN
 CASE strftime('%w', arrival) 
 WHEN '0' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)    
 WHEN '1' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)         
 WHEN '2' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)           
 WHEN '3' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)         
 WHEN '4' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)         
 WHEN '5' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)          
 WHEN '6' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 1)
 END
WHEN '1' THEN
 CASE strftime('%w', arrival) 
 WHEN '0' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)  
 WHEN '1' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)          
 WHEN '2' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)           
 WHEN '3' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)           
 WHEN '4' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)           
 WHEN '5' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)           
 WHEN '6' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 1)
 END
WHEN '2' THEN
 CASE strftime('%w', arrival) 
 WHEN '0' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)      
 WHEN '1' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)           
 WHEN '2' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '3' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)            
 WHEN '4' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)            
 WHEN '5' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)       
 WHEN '6' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 1) 
 END
WHEN '3' THEN
 CASE strftime('%w', arrival) 
 WHEN '0' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)      
 WHEN '1' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)           
 WHEN '2' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '3' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '4' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)            
 WHEN '5' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)            
 WHEN '6' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 1) 
 END
WHEN '4' THEN
 CASE strftime('%w', arrival) 
 WHEN '0' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)      
 WHEN '1' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)           
 WHEN '2' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '3' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '4' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)           
 WHEN '5' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 0)           
 WHEN '6' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 1)
 END
WHEN '5' THEN
 CASE strftime('%w', arrival)
 WHEN '0' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)      
 WHEN '1' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)           
 WHEN '2' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '3' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '4' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '5' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '6' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 1)
 END
WHEN '6' THEN
 CASE strftime('%w', arrival) 
 WHEN '0' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)      
 WHEN '1' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)           
 WHEN '2' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '3' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '4' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '5' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2)            
 WHEN '6' THEN ((cast((julianday(released)-julianday(arrival)) / 7 as int) * 2) + 2) 
 END
END
END

), avg(julianday(released)-julianday(arrival))
from trucks

（注意：avg(julianday(released)-julianday(arrival))末尾的只是为了测试目的，以表明新计算的平均值实际上小于两个日期之间差异的直接平均值）。

Answer 3

我在搜索 SQLite 是否具有工作日功能时发现了这篇文章。如果您使用最佳答案，则一周中的几天不太可能获得非常可靠的值。这是我用于我的项目的代码，它计算在 SpiceWorks 中创建票证和关闭票证之间的工作日：

SELECT t.id
,t.summary
,t.category
,u.email
,(CAST(strftime('%j', t.closed_at) as INTEGER) - CAST(strftime('%j', t.created_at) as INTEGER) - /*I can't figure it out, but julianday() wasn't giving me the correct distances for some numbers. I used the day of the year, instead, which resolved things as expected*/
    CASE                                                    
    WHEN CAST(strftime('%W', t.closed_at) as INTEGER) - CAST(strftime('%W', t.created_at) as INTEGER) = 0 THEN 0 /*If they are in the same week then there is no weekend to count. If you closed a ticket, that was opened on a Monday, on Saturday, then you must of worked on Saturday and therefore counts as work day the same as if you finished it on Monday*/
    WHEN CAST(strftime('%w', t.created_at) as INTEGER) = 0 THEN (CAST(strftime('%W', t.closed_at) as INTEGER) - CAST(strftime('%W', t.created_at) as INTEGER)) * 2 - 1 /*If they made their ticket on Sunday, don't count that Sunday*/
    WHEN CAST(strftime('%w', t.created_at) as INTEGER) = 6 THEN (CAST(strftime('%W', t.closed_at) as INTEGER) - CAST(strftime('%W', t.created_at) as INTEGER)) * 2 - 2 /*If they made their ticket on Saturday, don't count that Saturday*/
    ELSE (CAST(strftime('%W', t.closed_at) as INTEGER) - CAST(strftime('%W', t.created_at) as INTEGER)) * 2 /*Ignoring the possibility for closed dates that happen before open dates, take the number of weeks between each date and assume each had a Saturday and Sunday within them*/
    END) as 'Week Days Elapsed' /*This equation in full represents: Full_Distance_In_Days_Between - Number of weekend days calculated*/
    FROM Tickets as t
    LEFT JOIN Users as u
    on t.created_by = u.id
    WHERE  strftime('%Y-%m', t.created_at) = strftime('%Y-%m', 'now')