title: Handling time zone in web application
body: <p>In our web application we need to show and enter 
  date time information for different countries in different time zone. Right now, we are maintaining separate web server and separate database (oracle 11g) for each country.</p>
  
  <p>We are planning to merge all into one portal with single database (oracle 11g).
  This portal should capture/display date and time in user local time zone.</p>
  
  <p>So far, I have searched about this, I got below suggestion.</p>
  
  <p>1) set web server's and database server's time zone to UTC and while fetching data (data and time) convert into user local time zone.</p>
  
  <p>If you suggest this approach then please clarify the following specific
  questions. </p>
  
  <ul>
  <li><p>most of the time we are capturing date alone, is it require to
  capture date and time along with time zone always? </p></li>
  <li><p>while storing date and time where we need to convert user local time
  zone to UTC in javascript/java/oracle? </p></li>
  <li><p>while fetching date and time where we need to convert UTC to user<br>
  local time zone query itself/java/java script?      </p></li>
  <li><p>many place we have reports to show based on date column such as<br>
  today/current month/date range.how we can handle this(input - user
  local time zone - database in UTC)?</p></li>
  <li>which data type we have to use for date field
  (date/timestamp/timestamp with time zone/timestamp with local time
  zone)?</li>
  </ul>
  
  <p>2) capture date and time in both user local time zone and UTC. Stored as separate columns, user local time zone will be used for display purpose and UTC will be used for business logic.</p>
  
  <p>If you suggest this approach then please clarify the following specific
  questions.</p>
  
  <ul>
  <li><p>Is it common practice to store the user local time zone and UTC?</p></li>
  <li><p>which column i have to check condition while fetching reports to show
  based on date column such as today/current month/date range?</p></li>
  <li><p>which data type we have to use for date column<br>
  (date/timestamp/timestamp with time zone/timestamp with local time<br>
  zone)?</p></li>
  </ul>
  
  <p>thanks in advance</p>