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I want to convert this sql code to firebird sql for find working days between two dates:

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

)

thanks

4

1 回答 1

1

您当前的 SQL Server 函数是一个表值函数（它返回一个表），Firebird 3（及更早版本）中最接近的等效函数是一个可选择的存储过程：

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

星期差的to和from日期到星期天的标准化是必要的，因为不幸的是datediff(week ...)Firebird 不计算星期，但是两个日期之间有 7 天的周期，所以例如datediff(week, date'2017-07-14', date'2017-07-20')（星期五到下星期四）是 0 ，而不是 1。标准化到一周中的星期日将确保正确计算周差。

一个警告：我只用（小）日期选择测试了它，并将它与 SQL Server 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它。

鉴于数据的性质，您还可以在 SQL Server 中使用标量函数。标量函数的等价物是PSQL 函数（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：

于 2017-07-15T09:43:36.023 回答