I am running MYSQL 4.1 database that stores call center data for our offices that operate in Europe.
My MYSQL database sits on a Windows 2003 server that's has its time zone set to Central European Time, which automatically adjusts to day light savings.
I want to able to produce a report that shows the log date and time in the correct time zone to our customers in Europe.
My database stores the log date / time of the call as a unix time stamp. So therefore the dates stored as UTC. I found MYSQL function that can easily adjust the log date time to a time zone of your choice.
It's called CONVERT_TZ. (More info:http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_convert-tz)
Example: SELECT CONVERT_TZ('2004-01-01 12:00:00','UTC','CET');
I tried to apply this to call that was logged on 01-06-2013 22:12
CONVERT_TZ(FROM_UNIXTIME(o.logdatex), 'UTC','CET') 'CET_L_DATETIME'
(logdatex is the unxtimestamp for when the call was logged)
To my confusion the statement returned - 2013-06-02 00:12:56.
I wanted to see what was returned when I just selected FROM_UNIXTIME(o.logdatex)
It returned the correct time! 2013-06-01 22:12:56 (This call was logged from our Amsterdam office)
My question is, does the FROM_UNIXTIME function automatically adjust the time from UTC according to what the time zone MYSQL server is set to? I cannot find any documentation that says it does.
My assumption this is because when you do FROM_UNIXTIME(o.logdatex) you convert from UTC to timezone of your server.
And now you date is not in UTC timezone. So in CONVERT_TZ(FROM_UNIXTIME(o.logdatex), 'UTC','CET') you don't convert from 'UTC' but from timezone of your server so you get a strange result for you.
Try to select FROM_UNIXTIME(o.logdatex) as a separate field in your query and compare results.
Related
I am working on Hbase database and using apache Phoenix to access Hbase using normal SQL queries.
I have two columns in table which holds the current UTC timestamp in varchar and Date. after loading some data and when I query back Hbase I am getting strange results for event timestamp column which is of Date type.
Event UTC (Date) :2017-01-13 16:36:59.0
Event UTC (varchar):2017-01-13 21:36:59
above two values should be identical but for each record when querying back Event UTC ( Date) column giving me wrong result i.e exactly 5 hours behind.
I dont know from where this problem is coming .I am not saving any Timezone info and I am aware that Java Util or SQL timestamp doesnt store any time zone info, But really confused with the result set data when running a query. Please Help me in resolving this issue
Most likely it is because of the client's local time zone.
From official docs
Timestamp type:
the internal representation is based on a number of milliseconds since the epoch (which is based on a time in GMT), while java.sql.Timestamp will format timestamps based on the client's local time zone.
I have a report with two parameters - StartDate and EndDate - which run a stored procedure that returns data between these two dates.
The dates in the database are stored in UTC. Currently in the UK we are on BST (UTC+1).
To show the times in the correct time zone, in the report I am using System.TimeZone.CurrentTimeZone.ToLocalTime.
The end result is that the times as displayed on the report look correct, but the user still has to enter the StartDate and EndDate parameters in UTC. This confuses the user greatly as they expect to be able to enter a date in the current time zone, but the times in the database are UTC.
How can I allow the date parameters to be entered in the correct time zone?
Unfortunately, we can't modify the schema of the database so I need to find a way to fix this on the reporting side
In SSRS, if the date stored in database is UTC, it has to be UTC when select from a query in parameter setting. It is not supported to change the field which is from a query in parameter. For your requirement, you can either format the date into local time in query. Or you can select UTC date in parameter, and render it as local time
I run the following MySQL query:
select unix_timestamp('2011-03-13 02:00:13'), unix_timestamp('2011-03-13 02:20:41'), unix_timestamp('2011-03-13 02:40:10');
And get the following odd result:
1300003200, 1300003200, 1300003200
I think there's some kind of daylight savings time going on here, though it still seems odd that all the values are magically the same.
I'd appreciate suggestions of how to prevent MySQL from doing daylight savings time things here, as well as some explanation as to why all the results are the same.
MySQL's behavior is correct, if your server's time zone "CDT" observes DST and you haven't set your session time zone to something different.
The UNIX_TIMESTAMP() function uses your session's time zone to interepret the value you give it.
The server interprets date as a value in the current time zone and converts it to an internal value in UTC.
...
Note: If you use UNIX_TIMESTAMP() and FROM_UNIXTIME() to convert between TIMESTAMP values and Unix timestamp values, the conversion is lossy because the mapping is not one-to-one in both directions. For example, due to conventions for local time zone changes, it is possible for two UNIX_TIMESTAMP() to map two TIMESTAMP values to the same Unix timestamp value. FROM_UNIXTIME() will map that value back to only one of the original TIMESTAMP values.
— http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_unix-timestamp
The timestamps in question did not exist in your time zone, so the server is giving you the most accurate possible answer... it's the time in UTC that the clock moved forward to, when the time moved forward, less than an hour prior to your datetime literals, which represent "times that never existed on that day" in your time zone.
If those timestamps are intended to be times in your local time zone, then the answer is that those are invalid values, since that time never happened where you are. On the other hand, if those timestamps are actually assumed to already be in UTC, then you're not getting the correct answer from UNIX_TIMESTAMP() on any query, because the time is being converted "from" a time zone it isn't actually expressed in.
If you SET ##TIME_ZONE = 'UTC'; and repeat the queries, you'll see what I mean, since UTC has no DST. This statment only sets your session's time zone, not the whole server.
If running SET ##TIME_ZONE = 'UTC'; gives you an error message such as ERROR 1298 (HY000): Unknown or incorrect time zone: 'UTC', it is likely that you have not populated MySQL with timezone information. As described here you can load this information by using the command:
mysql_tzinfo_to_sql /usr/share/zoneinfo/ | mysql -u root mysql -p
where the path /usr/share/zoneinfo may need to be replaced with a path specific to your system.
According to mysqltutorial
The values of the MySQL TIMESTAMP columns depend on connection’s time
zone. When insert values for MySQL TIMESTAMP columns, they are
converted to Universal Coordinated Time (UTC) from connection’s time
zone. When you select the value, the server converts it back from UTC
to the connection’s time zone so you have the same value that you
inserted.
Where does it get this info. from, the time the user sets his OS to or from some other method?
Javascript also has a way to do timezones but is more involved: onlineaspect
To specify connection-specific time you need to perform
SET time_zone = TZ;
Where TZ can be either numerical offset like +11:00 or name of timezone Asia/Vladivostok (for the latter you need to import timezones description. Ask your DBA to do so)
the example there is wrong, i just tested it. it returns the previously inserted timestamp, regardless of the timezone. mysql will always insert the time you specify, without modifying it. if you need timezone adjustment, you have to tell mysql explicit to do so; otherwise all times are assumed to be "local server time".
Say I have multiple servers in multiple locations and I want to use MySQL's datetime type for the field date and I always want to have the field date have the UTC timestamp so I would execute a UTC_TIMESTAMP() when I add it to the database. Now say I want to have MySQL output the UNIX TIMESTAMP for it.
When I do this on Server A I get the string "2009-06-17 12:00:00" doing the UNIX_TIMESTAMP(STRING) on it gives me the number 1245240000 back. Which is 2009-06-17 12:00:00 in UTC time. Now I do the same thing on Server B.
I get the same string back since its the UTC string but when executing UNIX_TIMESTAMP(STRING) again I get back the wrong number back 1245232800 which is the UTC +2 time. How do I get around this? Should I do the convertion from string to timestamp on the PHP side?
G'day,
I'll ask the obvious here, did you check the date and time on both machines?
Edit: ... and the MySQL timezone was the same on both machines?
Update: Ok. The problem is in the fact that the timestamp string being passed into UNIX_TIMESTAMP is interpreted to be a value in the current timezone which is then converted back to UTC so, because you're in MEZ, two hours is subtracted to return it back to UTC so 7200 is subtracted from your timestamp when it is converted back to a Unix timestring.
Hence, the variation you see when using UNIX_TIMESTAMP() to convert is back to a Unix Epoch timestring.
BTW Shouldn't you be using a TIMESTAMP type for storing off your UTC_TIMESTAMPs instead of DATETIME type?
Update: Decoupling presentation time from stored time is definitely the way to go. You can then reuse the same data all around the world and only have to convert to and from local time when you are presenting the data to a user.
If you don't do this then you are going to have to store off the timezone when the timestamp was made and then go into all sorts of complicated permutations of having to work out if
the local timezone was in daylight saving time when it was stored,
what the difference is between the timezone at the time that the data was stored and the timezone where the data is to be presented.
Leaving it all storeed as UTC gets rid of that.
Most users won't be that happy if they have to work out the local time themselves based on the UTC time returned so systems usually convert to current local time for the user.
This is of course if the user wants the data expressed in local time which is usually the case. The only widely used system I can think of, off the top of my head, that stores and presents its data in UTC is system for air traffic control and flight plan management which are always kept in UTC (or ZULU time to be more precise).
HTH
cheers,
Have you tried doing this?
Execute this instructions together.
SET time_zone = 'UTC';
SELECT FROM_UNIXTIME(0), UNIX_TIMESTAMP('2009-06-17 12:00:00');
// 1970-01-01 00:00:00 1245240000
They only affect the client session, not the server configuration.