计算特定年份的sql中的日期差异

Posted 2023-04-19

【中文标题】计算特定年份的sql中的日期差异

【英文标题】：Calculate date difference in sql for specific year

【发布时间】：2015-07-23 11:11:44

【问题描述】：

我有两个日期，比如 start_date 是 20141215 和 end_date = 20150115。我想使用 SQL DATEDIFF 只计算我将在查询中指定的 2015 年的日期。这是我编写的当前 SQL：

SELECT COUNT(leave_id), 
    sum(case when leave_status = 1 then 1 else 0 end) pending, 
    sum(case when leave_status = 2 then 1 else 0 end) declined, 
    sum(case when leave_status = 3 then 1 else 0 end) approved,
    sum(case when leave_status = 4 then 1 else 0 end) rostered,
    SUM(DATEDIFF(end_date, start_date)+1) as datetotals
    FROM employee_leave WHERE 
    ((YEAR(start_date) = :year) OR (YEAR(end_date) = :year)) 
    AND employee_id = :emp_id

谢谢

【参考方案1】：

您需要修复 datediff() 以仅考虑一年中的日期。我认为这可以满足您的要求：

SELECT COUNT(leave_id), 
       sum(case when leave_status = 1 then 1 else 0 end) pending, 
       sum(case when leave_status = 2 then 1 else 0 end) declined, 
       sum(case when leave_status = 3 then 1 else 0 end) approved,
       sum(case when leave_status = 4 then 1 else 0 end) rostered,
       SUM(DATEDIFF(least(end_date, date(concat_ws('-', :year, 12, 31))),
                    greatest(start_date, date(concat_ws('-', :year, 1, 1)))
                   ) + 1) as datetotals
FROM employee_leave 
WHERE ((YEAR(start_date) = :year) OR (YEAR(end_date) = :year)) AND
      employee_id = :emp_id

【讨论】：

感谢 Gordon，这非常适合我所追求的。

【参考方案2】：

使它成为AND 条件，而不是像

WHERE 
    ((YEAR(start_date) = :year) AND (YEAR(end_date) = :year))