MySQL runs with timezone “GMT+8”, but Tomcat with “GMT”. When I save datetime to my database, everything seems to be OK, but when I check the datetime value in the database, I see the “GMT” value.
Also when I try get the value from the database the value is changed, seems like the value in the database is taken as “GMT+8”, so Java changes the value to “GMT”.
I have set the connection URL like this:
useTimezone=true&serverTimezone=GMT
but it does not work.
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Answer
useTimezone is an older workaround. MySQL team rewrote the setTimestamp/getTimestamp code fairly recently, but it will only be enabled if you set the connection parameter useLegacyDatetimeCode=false and you’re using the latest version of mysql JDBC connector. So for example:
String url = "jdbc:mysql://localhost/mydb?useLegacyDatetimeCode=false
If you download the mysql-connector source code and look at setTimestamp, it’s very easy to see what’s happening:
If use legacy date time code = false, newSetTimestampInternal(…) is called. Then, if the Calendar passed to newSetTimestampInternal is NULL, your date object is formatted in the database’s time zone:
this.tsdf = new SimpleDateFormat("''yyyy-MM-dd HH:mm:ss", Locale.US);
this.tsdf.setTimeZone(this.connection.getServerTimezoneTZ());
timestampString = this.tsdf.format(x);
It’s very important that Calendar is null – so make sure you’re using:
setTimestamp(int,Timestamp).
… NOT setTimestamp(int,Timestamp,Calendar).
It should be obvious now how this works. If you construct a date: January 5, 2011 3:00 AM in America/Los_Angeles (or whatever time zone you want) using java.util.Calendar and call setTimestamp(1, myDate), then it will take your date, use SimpleDateFormat to format it in the database time zone. So if your DB is in America/New_York, it will construct the String ‘2011-01-05 6:00:00’ to be inserted (since NY is ahead of LA by 3 hours).
To retrieve the date, use getTimestamp(int) (without the Calendar). Once again it will use the database time zone to build a date.
Note: The webserver time zone is completely irrelevant now! If you don’t set useLegacyDatetimecode to false, the webserver time zone is used for formatting – adding lots of confusion.
Note:
It’s possible MySQL my complain that the server time zone is ambiguous. For example, if your database is set to use EST, there might be several possible EST time zones in Java, so you can clarify this for mysql-connector by telling it exactly what the database time zone is:
String url = "jdbc:mysql://localhost/mydb?useLegacyDatetimeCode=false&serverTimezone=America/New_York";
You only need to do this if it complains.