How to combine date and time to datetime2 in SQL Server?

Given the following components DECLARE @D DATE = '2013-10-13' DECLARE @T TIME(7) = '23:59:59.9999999' What is the best way of combining them to produce a DATETIME2(7) result with value '2013-10-13 23:59:59.9999999'? Some things which **don't** work are listed below. --- SELECT @D + @T > Operand data type date is invalid for add operator. --- SELECT CAST(@D AS DATETIME2(7)) + @T > Operand data type datetime2 is invalid for add operator. --- SELECT DATEADD(NANOSECOND,DATEDIFF(NANOSECOND,CAST('00:00:00.0000000' AS TIME),@T),@D) > The datediff function resulted in an overflow. The number of dateparts > separating two date/time instances is too large. Try to use datediff > with a less precise datepart. \* The overflow can be avoided in Azure SQL Database and SQL Server 2016, using DATEDIFF_BIG . --- SELECT CAST(@D AS DATETIME) + @T > The data types datetime and time are incompatible in the add operator. --- SELECT CAST(@D AS DATETIME) + CAST(@T AS DATETIME) > Returns a result but loses precision 2013-10-13 23:59:59.997