Assume pt is a PERIOD(TIME(2)) column in table t with a value of PERIOD '(12:12:12.34, 12:12:12.35)'.
In the following example, a PERIOD(TIME(2)) column is cast as TIME(6). The TIME(6) result is obtained from the source beginning element with trailing zeros added to the fractional seconds to make the precision 6.
SELECT CAST(pt AS TIME(6)) FROM t;
The following is returned:
12:12:12.340000