SQL Server 2019

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declare @day_xls AS DECIMAL(20,10) = 36964
select dateadd(d,@day_xls,'1899-12-30')

(No column name)

2001-03-14 00:00:00.000

declare @time_xls AS DECIMAL(20,10) = 42853.4673621111
select dateadd(second, (@time_xls - ROUND(@time_xls,0))*86400, dateadd(d, ROUND(@time_xls,0),'1899-12-30'))

(No column name)

2017-04-28 11:13:00.000

Declare @datetime datetime = '2024-08-23 15:32:32.000'
Select cast(@datetime as float)+2

(No column name)

45527.6475925926