Constructs datetime descriptor.
procedure Construct(Year: smallint; Month: byte; Day: byte; Hour: byte; Min: byte; Sec: byte; FSec: cardinal; TimeZone: string);
Call the Construct method to construct datetime descriptor. When calling the Construct procedure only relevant fields based on the datetime type are used. For the type with time zone, the date and time fields are assumed to be in the local time of the specified time zone. If the time zone is not specified, then session default time zone is assumed.