Convert a Clarion Date (INT) to SQL DateTime

clariondate.sql

DECLARE @ClarionDate INT = 47563
DECLARE @SqlDateTime DATETIME 

-- Convert the clarion DATE into and SQL DateTime
SET @SqlDateTime = DateAdd(day, @ClarionDate  - 4, '1801-01-01') 

SELECT @SqlDateTime AS 'SQL Date Time'

-- Now convert it back from and SQL DateTime to a Clarion Date
SET @ClarionDate = DateDiff(day, DateAdd(day, -4, '1801-01-01'), @SqlDateTime)
SELECT @ClarionDate AS 'Clarion Date'

/*
A Clarion standard date is the number of days that have elapsed since 
December 28, 1800. The range of accessible dates is from January 1, 1801 
(standard date 4) to December 31, 9999 (standard date 2,994,626). Date 
procedures will not return correct values outside the limits of this range. 
The standard date calendar also adjusts for each leap year within the range of 
accessible dates. Dividing a standard date by modulo 7 gives you the day of the 
week: zero = Sunday, one = Monday, etc.

The LONG data type with a date format (@D) display picture is normally used for 
a standard date. Data entry into any date format picture with a two-digit year 
defaults to the century of next 20 or previous 80 years. For example, entering 
01/01/01 results in 01/01/2001 if the current year (per the system clock) is 
greater than 1980, and 01/01/1901 if the current year is 1980 or earlier.

The DATE data type is a data format used in the Btrieve Record Manager and some 
other file systems. A DATE field is internally converted to LONG containing the 
Clarion standard date before any mathematical or date procedure operation is 
performed. Therefore, DATE should be used for external file compatibility, and 
LONG is normally used for other dates.
*/

THANK YOU VERY MUCH!