I have to store UTC dateTime in DB.
I have converted the dateTime given in specific timezone to UTC. for that I followed the below code.
My input dateTime is "20121225 10:00:00 Z" timezone is "Asia/Calcutta"
My Server/DB(oracle) is running in the same timezone(IST) "Asia/Calcutta"
Get the Date object in this specific Timezone
String date = "20121225 10:00:00 Z";
String timeZoneId = "Asia/Calcutta";
TimeZone timeZone = TimeZone.getTimeZone(timeZoneId);
DateFormat dateFormatLocal = new SimpleDateFormat("yyyyMMdd HH:mm:ss z");
//This date object is given time and given timezone
java.util.Date parsedDate = dateFormatLocal.parse(date + " "
+ timeZone.getDisplayName(false, TimeZone.SHORT));
if (timeZone.inDaylightTime(parsedDate)) {
// We need to re-parse because we don't know if the date
// is DST until it is parsed...
parsedDate = dateFormatLocal.parse(date + " "
+ timeZone.getDisplayName(true, TimeZone.SHORT));
}
//assigning to the java.sql.TimeStamp instace variable
obj.setTsSchedStartTime(new java.sql.Timestamp(parsedDate.getTime()));
Store into DB
if (tsSchedStartTime != null) {
stmt.setTimestamp(11, tsSchedStartTime);
} else {
stmt.setNull(11, java.sql.Types.DATE);
}
OUTPUT
DB (oracle) has stored the same given dateTime: "20121225 10:00:00
not in UTC.
I have confirmed from the below sql.
select to_char(sched_start_time, 'yyyy/mm/dd hh24:mi:ss') from myTable
My DB server also running on the same timezone "Asia/Calcutta"
It gives me the below appearances
Date.getTime()
is not in UTC One more question:
Will timeStamp.toString()
print in local timezone like java.util.date
does? Not UTC?
You can use the below method to store the timestamp in database specific to your desired zone/zone Id.
ZonedDateTime zdt = ZonedDateTime.now(ZoneId.of("Asia/Calcutta")) ;
Timestamp timestamp = Timestamp.valueOf(zdt.toLocalDateTime());
A common mistake people do is use LocaleDateTime
to get the timestamp of that instant which discards any information specif to your zone even if you try to convert it later. It does not understand the Zone.
Please note Timestamp
is of the class java.sql.Timestamp
.
The answer is that java.sql.Timestamp
is a mess and should be avoided. Use java.time.LocalDateTime
instead.
So why is it a mess? From the java.sql.Timestamp
JavaDoc, a java.sql.Timestamp
is a "thin wrapper around java.util.Date
that allows the JDBC API to identify this as an SQL TIMESTAMP value". From the java.util.Date
JavaDoc, "the Date
class is intended to reflect coordinated universal time (UTC)". From the ISO SQL spec a TIMESTAMP WITHOUT TIME ZONE "is a data type that is datetime without time zone". TIMESTAMP is a short name for TIMESTAMP WITHOUT TIME ZONE. So a java.sql.Timestamp
"reflects" UTC while SQL TIMESTAMP is "without time zone".
Because java.sql.Timestamp
reflects UTC its methods apply conversions. This causes no end of confusion. From the SQL perspective it makes no sense to convert a SQL TIMESTAMP value to some other time zone as a TIMESTAMP has no time zone to convert from. What does it mean to convert 42 to Fahrenheit? It means nothing because 42 does not have temperature units. It's just a bare number. Similarly you can't convert a TIMESTAMP of 2020-07-22T10:38:00 to Americas/Los Angeles because 2020-07-22T10:30:00 is not in any time zone. It's not in UTC or GMT or anything else. It's a bare date time.
java.time.LocalDateTime
is also a bare date time. It does not have a time zone, exactly like SQL TIMESTAMP. None of its methods apply any kind of time zone conversion which makes its behavior much easier to predict and understand. So don't use java.sql.Timestamp
. Use java.time.LocalDateTime
.
LocalDateTime ldt = rs.getObject(col, LocalDateTime.class);
ps.setObject(param, ldt, JDBCType.TIMESTAMP);
It is specific from your driver. You need to supply a parameter in your Java program to tell it the time zone you want to use.
java -Duser.timezone="America/New_York" GetCurrentDateTimeZone
Further this:
to_char(new_time(sched_start_time, 'CURRENT_TIMEZONE', 'NEW_TIMEZONE'), 'MM/DD/YY HH:MI AM')
May also be of value in handling the conversion properly. Taken from here
I think the correct answer should be java.sql.Timestamp is NOT timezone specific. Timestamp is a composite of java.util.Date and a separate nanoseconds value. There is no timezone information in this class. Thus just as Date this class simply holds the number of milliseconds since January 1, 1970, 00:00:00 GMT + nanos.
In PreparedStatement.setTimestamp(int parameterIndex, Timestamp x, Calendar cal) Calendar is used by the driver to change the default timezone. But Timestamp still holds milliseconds in GMT.
API is unclear about how exactly JDBC driver is supposed to use Calendar. Providers seem to feel free about how to interpret it, e.g. last time I worked with MySQL 5.5 Calendar the driver simply ignored Calendar in both PreparedStatement.setTimestamp and ResultSet.getTimestamp.
For Mysql, we have a limitation. In the driver Mysql doc, we have :
The following are some known issues and limitations for MySQL Connector/J: When Connector/J retrieves timestamps for a daylight saving time (DST) switch day using the getTimeStamp() method on the result set, some of the returned values might be wrong. The errors can be avoided by using the following connection options when connecting to a database:
useTimezone=true
useLegacyDatetimeCode=false
serverTimezone=UTC
So, when we do not use this parameters and we call setTimestamp or getTimestamp
with calendar or without calendar, we have the timestamp in the jvm timezone.
Example :
The jvm timezone is GMT+2. In the database, we have a timestamp : 1461100256 = 19/04/16 21:10:56,000000000 GMT
Properties props = new Properties();
props.setProperty("user", "root");
props.setProperty("password", "");
props.setProperty("useTimezone", "true");
props.setProperty("useLegacyDatetimeCode", "false");
props.setProperty("serverTimezone", "UTC");
Connection con = DriverManager.getConnection(conString, props);
......
Calendar nowGMT = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
Calendar nowGMTPlus4 = Calendar.getInstance(TimeZone.getTimeZone("GMT+4"));
......
rs.getTimestamp("timestampColumn");//Oracle driver convert date to jvm timezone and Mysql convert date to GMT (specified in the parameter)
rs.getTimestamp("timestampColumn", nowGMT);//convert date to GMT
rs.getTimestamp("timestampColumn", nowGMTPlus4);//convert date to GMT+4 timezone
The first method returns : 1461100256000 = 19/04/2016 - 21:10:56 GMT
The second method returns : 1461100256000 = 19/04/2016 - 21:10:56 GMT
The third method returns : 1461085856000 = 19/04/2016 - 17:10:56 GMT
Instead of Oracle, when we use the same calls, we have :
The first method returns : 1461093056000 = 19/04/2016 - 19:10:56 GMT
The second method returns : 1461100256000 = 19/04/2016 - 21:10:56 GMT
The third method returns : 1461085856000 = 19/04/2016 - 17:10:56 GMT
NB : It is not necessary to specify the parameters for Oracle.
Source: Stackoverflow.com