When Derby Reference Manual, version 10.4, explains the INTEGER function is said that:
"The INTEGER function returns an integer representation of a number, character string,
DATE, or time in the form of an integer constant"
But when I try to convert a DATE to INTEGER I receive an sqlstate 42846: "Cannot convert types 'DATE' to 'INTEGER'."
This is a sample query where the expected result is the integer number 1:
select integer(date(1)) from SYSIBM.SYSDUMMY1