A PERIOD(DATE), PERIOD(TIME(n) [WITH TIME ZONE]), or PERIOD(TIMESTAMP(n) [WITH TIME ZONE]) value can be cast as TIMESTAMP[(n)] [WITH TIME ZONE] using the CAST function. The source last value must be equal to the source beginning bound; otherwise, an error is reported.
If the source type is PERIOD(TIME(n) [WITH TIME ZONE]) or PERIOD(TIMESTAMP(n) [WITH TIME ZONE]):
- If the target precision is higher than the source precision, trailing zeros are added in the result to adjust the precision.
- If the target precision is lower than the source precision, an error is reported.
If the source type is PERIOD(DATE), the result is formed from the source beginning bound and a time portion of 0 adjusted with respect to the current session time zone, and, if the target type is WITH TIME ZONE, the current session time zone displacement.
If the source type is PERIOD(TIME(n) [WITH TIME ZONE]), the source beginning bound (in UTC) is adjusted with respect to the current session time zone displacement. The timestamp portion of the result is formed from CURRENT_DATE and the time portion of the source beginning bound obtained after the adjustment. The resulting timestamp value is converted to UTC. If both the source and target type are WITH TIME ZONE, the result time zone field is set to the time zone displacement of the source beginning bound. If only the target type is WITH TIME ZONE, the result time zone field is set to the current session time zone displacement.
If the source type is PERIOD(TIMESTAMP(n) [WITH TIME ZONE]), the result timestamp portion is the timestamp portion of the source beginning bound. If both the source and target type are WITH TIME ZONE, the result time zone field is set to the time zone displacement of the source beginning bound. If only the target type is WITH TIME ZONE, the result time zone field is set to the current session time zone displacement.