日期跳过周末之间的火鸟计算

Question

我想将此 sql 代码转换为 firebird sql 以查找两个日期之间的工作日：

CREATE FUNCTION [dbo].fn_CountWeekDays
(
@fromdate Datetime,
@todate Datetime
)
RETURNS TABLE AS RETURN
(

 SELECT
(DATEDIFF(dd, @fromdate, @todate) + 1)
-(DATEDIFF(wk, @fromdate, @todate) * 2)
-(CASE WHEN DATENAME(dw, @fromdate) = 'Sunday' THEN 1 ELSE 0 END)
-(CASE WHEN DATENAME(dw, @todate) = 'Saturday' THEN 1 ELSE 0 END)
As NoOfWeekDays

)

谢谢

Answer 1

您当前的 SQL 服务器函数是一个 table 值函数（它 returns 一个 table），Firebird 3（及更早版本）中最接近的等效函数将是一个选择table存储过程：

create or alter procedure CountWeekDays(fromdate timestamp, todate timestamp)
returns (NoOfWeekDays bigint)
as
declare normalizedFrom timestamp;
declare normalizedTo timestamp;
begin
    normalizedFrom = dateadd(-1 * extract(weekday from fromdate) day to fromdate);
    normalizedTo = dateadd(-1 * extract(weekday from todate) day to todate);
    NoOfWeekDays = (DATEDIFF(day, fromdate, todate) + 1)
            -(DATEDIFF(week, normalizedFrom , normalizedTo) * 2)
            -(CASE WHEN extract(weekday from fromdate) = 0 THEN 1 ELSE 0 END)
            -(CASE WHEN extract(weekday from todate) = 6 THEN 1 ELSE 0 END);
    -- Suspend is necessary to make it selectable!
    suspend;
end

将到和从日期标准化为星期日是必要的，不幸的是 datediff(week ...) Firebird 不计算周数，而是计算两个日期之间的 7 天时间段，因此例如 datediff(week, date'2017-07-14', date'2017-07-20')（星期五到下星期四）是 0，而不是 1。标准化为一周中的星期日将确保周差计算正确。

一个警告：我只用（小）日期选择对此进行了测试，并将其与 SQL 服务器函数的输出进行了比较，我没有用时间组件进行测试，你可能想更彻底地验证一下。

鉴于数据的性质，您也可以在 SQL 服务器中使用标量函数。标量函数的等效项是 PSQL function（在 Firebird 3 中引入）

create or alter function fn_CountWeekDays(fromdate timestamp, todate timestamp)
returns bigint
as
declare normalizedFrom timestamp;
declare normalizedTo timestamp;
begin 
    normalizedFrom = dateadd(-1 * extract(weekday from fromdate) day to fromdate);
    normalizedTo = dateadd(-1 * extract(weekday from todate) day to todate);
    return (DATEDIFF(day, fromdate, todate) + 1)
            -(DATEDIFF(week, normalizedFrom , normalizedTo) * 2)
            -(CASE WHEN extract(weekday from fromdate) = 0 THEN 1 ELSE 0 END)
            -(CASE WHEN extract(weekday from todate) = 6 THEN 1 ELSE 0 END);
end

参考文献：

日期跳过周末之间的火鸟计算

Firebird calc between date skip weekend

sql

firebird

firebird-3.0