How do I change TimeStamp from US server to UK time

Question

Hello,
I am based in the UK. My hosting company is based in the US. I am using a MySql database. All the database tables have timestamps that are set to the local machine time.
I would like to change the timestamp so that it is GMT.
Can you please tell me how I would go about doing this?
Is their any code available to enable me to insert the timestamp as a GMT date or do I set the value from the mysql database end.
Thanks
Andrew

Answer 1

Timestamp values in Java (java.sql.Timestamp) are GMT internally (actually, they're implemented as a long giving the number of milliseconds since 1. january, 1970).
Date values in SQL, on the other hand, are normally stored in the local time zone.
What you need to do, is tell JDBC what time zone you want the stored values to be in, like this:
When inserting (using a PreparedStatement):
  stmt.setTimestamp(column, myTimestamp, Calendar.getInstance(TimeZone.getTimeZone("GMT")));When reading back from a ResultSet:
  Timestamp ts = rs.getTimestamp(column, Calendar.getInstance(TimeZone.getTimeZone("GMT")));Now, you know that the timestamp value you've read back from the database does not have any bias to it introduced by the local timezone of the database server. The next step is to represent the Java Timestamp value to the user, and at this stage you may want to specify which time zone you want for the rendered timestamp, like this:
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  // convert the Timestamp to a String in a controlled manner
  // see the documentation for SimpleDateFormat for how you specify the format string
  DateFormat df = new SimpleDateFormat("yyyy.MM.dd HH.mm.ss");
  // need to set the time zone, or the server's time zone will be used
  // if you can somehow figure out the time zone where the user is
  // sitting, you may use that instead, to provide dates relative to
  // the user instead of the server
  df.setTimeZone(TimeZone.getTimeZone("GMT"));
  String outValue = df.format(myTimestamp);
  // output the converted value, maybe
  System.out.println(outValue);Similarly, you may use the parse() method of DateFormat to parse a String as a java.util.Date, which may then be converted into a Timestamp.
The general principles are as follows:
- internally, Java Timestamps, Dates etc. are stored relative to 1. january 1970, GMT
- when getting date values into or out of Java, time zones may have to be considered
- for converting to/from Strings (eg. for UI purposes), use the java.text.DateFormat class
- for communicationg with an SQL database via JDBC, use the set/get-Timestamp methods with the added Calendar argument
NB! Please be aware that I didn't actually try to compile this code, so bugs may be present.