Description:
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Using in my where clause, DATEPART (dw , dt.usedate) = 1 returns random results toggling between SUNDAY AND MONDAY. Switch to DATENAME (dw , dt.usedate) = 'Sunday' and it works fine. This code worked fine in 4.2. 

date_table is a table with all dates between 1900 to 2050.

Reproduce code:
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$query = mssql_query("	SELECT 	dt.usedate					FROM 	date_table dt					WHERE	dt.usedate between '$s_reportdate' AND '$e_reportdate' AND	DATEPART (dw , dt.usedate) = 1
ORDER BY DT.usedate");

Expected result:
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Should return Sunday dates between range provided.

Actual result:
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Returns seemingly random results of either a Monday or Sunday date. If I add DATEPART (dw , dt.usedate) as blah into the select clause it returns 1 every time but the dates still shift.