-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Terence,
On 1/7/20 7:33 PM, Terence M. Bandoian wrote: > On 1/7/2020 4:04 PM, Zahid Rahman wrote: >> Jerry Malcolm wrote : >> >>> Again this is the SAME line of code in java reading the >>> >SAME >> field in >>> the SAME database. Only thing different is >Linux/Windows OS >> >> >> >> On Tue, 7 Jan 2020, 21:52 , <john.e.gr...@wellsfargo.com.invalid> >> wrote: >> >>>> -----Original Message----- From: Jerry Malcolm >>>> <techst...@malcolms.com> Sent: Tuesday, January 07, 2020 3:14 >>>> PM To: users@tomcat.apache.org Subject: Re: Dates on Linux >>>> vs. Windows >>>> >>>> On 1/7/2020 3:09 PM, Michael Osipov wrote: >>>>> Am 2020-01-07 um 21:58 schrieb Jerry Malcolm: >>>>>> This may be more of a Java question than Tomcat. But I'm >>>>>> not sure. I have the same code, talking to the same MySql >>>>>> Linux (AWS) database. I read a date column value in a >>>>>> Tomcat app. After calling resultSet.getDate(...) I >>>>>> printed the date instance and the getTime() value: >>>>>> >>>>>> On windows: 2019-02-01 1549000800000 >>>>>> >>>>>> On linux: 2019-01-31 1548979200000 >>>>>> >>>>>> Again this is the SAME line of code in java reading the >>>>>> SAME field in the SAME database. Only thing different is >>>>>> Linux/Windows OS. The date is supposed to be 2/1/2019 >>>>>> and shows that in phpMyAdmin. >>>>>> >>>>>> I've been running on Linux for a few months. But I don't >>>>>> have an extensive background in the specifics of Linux. >>>>>> I'm sure there must be something that is configured >>>>>> differently. I'm at a loss. But this is not a trivial >>>>>> problem. I do monthly billing. My dates need to be >>>>>> accurate. >>>>> Have you verified that you aren't tricked by any timezone >>>>> issues? >>>> Probably so. But how would I know? I was under the >>>> impression that java.sql.Date was timezone independent. >>>> Shouldn't it simply convert a month/day/year value to the >>>> number of milliseconds since the epoch? How would timezone >>>> issues affect that? And if I am 'tricked' how do I >>>> 'untrick'. What do I set/change? >>>>> >>> Those millisecond values are 6 hours apart, which looks like a >>> timezone issue. I happen to be in US Central time, which is 6 >>> hours earlier than UTC in winter. >>> >>> You're right that System.currentTimeMillis() itself is >>> independent of timezone but Date is not. > > As I understand it, for certain date/time column types, MySQL > subtracts the time zone from the value when written and adds it > back in when read. If your systems always use the same time zone > to read and write the data, it isn't a problem. But it can be if > the time zone varies. > > See https://dev.mysql.com/doc/refman/5.7/en/datetime.html Only for TIMESTAMP columns, which are fairly rarely used. Usually, you want a DATETIME field, which is a SQL standard. > The actual behavior is a little confusing, at least to me, because > I seem to remember variations in the storage of the date/time > columns while the documentation seems to indicate that date/time > values are not modified. Also, if I remember correctly, writing a > date/time value as a formatted string and then reading it back as a > string (e.g. ResultSet.getString) and parsing it circumvented the > time zone issue. I've never had the intestinal fortitude to change the time zone on a running MySQL server. So I'm not sure if it would shift every DATETIME value I've ever written to it. Yikes, I'm using local time. I hope I remember that for every server I ever migrate to. - -chris -----BEGIN PGP SIGNATURE----- Comment: Using GnuPG with Thunderbird - https://www.enigmail.net/ iQIzBAEBCAAdFiEEMmKgYcQvxMe7tcJcHPApP6U8pFgFAl4VJrMACgkQHPApP6U8 pFgfyhAAu4jR5+hzu9oJJX9yN2rDeVw+3yGmHsiBF6eAZPUh7BLUkVV+kuhVxC+X pqWAvgStzyUAt/L7mdxNbNhyDSBMn5WJgjenQ70eLTqg+u3PYtkB/S+zxDgfwRbN x5WOzj/N1ypapdXCOZu7JnkmyL9tLQ1F+KfRIXPE9L6phlg4kDDvfvn9CGn+L/ir YkWtDk6YcNiWo4tguYj3lXNQ68CGBM2gkYKjWVtNKO1Keit8w/GgHbXnm9QmzEX8 jeXAL1LO4kUVEZayfaEmaLaSVfltR6ROB1Ubx4KNMG777wy9ln0odP1KSdWcmq+u Fu5kdsB25B+pxym0tPA21xIieGUp/4txCQn5WX66aLVS8CDgrWnl0uSP8iatZmPO wKL6i4qCEfPXYNTzB+CcLBuiK/8PXqcnp3YO2Xj2nqvh4pqqmkCUgJBM5umQVmhR 7iH3T1LjWhOPEBUx50Vz7+Dd7yj4Z6CZ/ubRYXTWXmUifu8hO2d1YehYj0ean+3r LaiTsmOHH9Tw1RDn+Wae4TCS+YEZZMLytSF2HnvXko87b/pU6eguapbO1ScBUepv KFhAUWUAzPtdvf2aZhveVscLCFGR1+Jl3Zv31qjSSriPuB3shRpWa2Q+g0/KPwrl zw3NiPsaIWL5hvxKdBllOKCMqoI7BwDlTkNocqb0QbHrYB5qcoA= =ETH9 -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
