Modifying User-defined Type Variable and Parameter Values
You can modify variables and parameters of a user-defined type in a SET statement or in the SELECT list of a SELECT statement. In either case, you modify values either by setting an individual property of the user-defined type value, or by invoking a state-modifying method on the instance of the type. To do this, you must have EXECUTE permission on the type.
This example sets a value for a user-defined type point by modifying the value of the type's property X.
DECLARE @p Point
SET @p.X = @p.X + 1.1
SELECT @p
GO
To modify a user-defined type variable or parameter value