Alan Burlison wrote:
I have been looking at the derby documentation for TIMESTAMP, and it's
pretty confusing when it comet to try to figure what will happen if I
move a database onto a machine in a different timezone.
http://db.apache.org/derby/papers/JDBCImplementation.html#Derby+SQL+TIMESTAMP
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Derby’s SQL TIMESTAMP type represents a time of day in the form
yyyy-mm-dd hh:mm:ss.fffffffff (nanosecond granularity) with no
associated time zone information.
java.sql.Timestamp
A JDBC Timestamp (java.sql.Timestamp) by definition represents a point
in time, with nanosecond resolution, in a given time zone.
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So what does "no associated timezone information" mean? Does Derby
normalize all timestamps to UTC, or does it just throw away the timezone
information altogether? If it is the second, that makes it impossible
to move databases across timezones without having to recalculate any
timestamps it uses.
It is the second, which is defined by the SQL standard which has
datetime values with and without timezone. In SQL terms (section 4.6 of
the SQL standard foundation document) Derby's TIMESTAMP is
TIMESTAMP WITHOUT TIME ZONE
Dan.
