All of the topics discussed here in this blog comes from my real life encounters. They serve as references for future research. All of the data, contents and information presented in my entries have been altered and edited to protect the confidentiality and privacy of the clients.

Thursday, October 11, 2012

How to report data dynamically based on user's personal time zone setting -- Part 3

So from the last time I took a step further to solve the issue of reporting based on time zone, although it wasn't 100% correct, at least it opens up a few options. The conclusion there was that we need to find a way to dynamically choose the time zone offset value and use it for our time conversation. Where I was stuck was at the daylight saving changes that happens from all over the world.

Therefore, I have decided to introduce a time zone table that stores all of the time zone and the corresponding offset value. The table structure is like below, and I have manually added 2 rows, both are for GMT -6 time zone. However, one of the time zone is currently having DST in effect while the other doesn't:

Then, bring this table into OBIEE's model:

Now, let's create some dashboard prompts using these 2 columns:

Here on Time Zone prompt, I am applying the following expression to show the contend:

SELECT case when "Time Zone"."Time Zone" = '@{session.timeZone}' then "Time Zone"."Time Zone" end FROM "Capacity Management" where case when "Time Zone"."Time Zone" = '@{session.timeZone}' then "Time Zone"."Time Zone" end is not null

The previously discovered session variable 'timeZone' is truly handy here. So the idea is that, when the time zone column equals the locale name that's generated by user session, it will return that exact locale name which is also stored in the time zone table. The where clause eliminates all the other records which will be null in this case. Also, the default value of this prompt will be the session variable.

Now create the second prompt on offset value:

Now the second prompt is also coming from the same time zone table, this should record the offset value that matches the locale name in the table. To do some, in the 'SQL result' setting, I entered the following expression:

SELECT "Time Zone"."Offset Value" FROM "Time Zone" where  "Time Zone"."Time Zone" = '@{session.timeZone}'

Also, I have set a presentation variable which will pass this value into any filters or tables that need conversions. I call this variable 'Offset'.

So let's test this prompt on the dashboard with the first locale setting, which is central America time:

The result looks great. These fields are automatically populated.

Now change the locale setting to central time U.S & Canada:

Then refresh the log in again and we see it automatically updates:

Now, the rest is pretty straightforward.  Remember in my previous post where I was forced to use the following expression to convert my time stamp in my timestampadd function? 

Timestampadd(sql_tsi_day, cast(Substring(case when '@{session.timeZone}' = '(GMT) Casablanca, Monrovia' then '(GMT+00:00) Casablanca, Monrovia' when '@{session.timeZone}' = '(GMT) Greenwhich Mean Time: Dublin, Edinburgh, Lisbon, London' then '(GMT+00:00) Greenwhich Mean Time: Dublin, Edinburgh, Lisbon, London' when '@{session.timeZone}' = '' then '(GMT+00:00) Default' else '@{session.timeZone}' end From 5 for 3) as int)/24 , Date."Hour Date"

Now I can simply replace all these codes to the following:

Timestampadd(sql_tsi_day, @{offset}/24 , Date."Hour Date". 

This will take care of all scenarios..

From OBIEE's point of view, we are all done. So of course, we have to maintain our time zone table and we have to figure out what offset value is for each time zone and when is their DST start and end date of the year. I went to wikipedia and it was pretty eye opening and fun to learn all these stuffs. 

So then, I will load the entire table with all of the time zone name and offset values. Some script will have to be called on specific day to update the offset value for DST. Although this may sound complicated, it is not in real life. Think about this, most of the time we will be supporting business in Asia, Europe, North America, South America or Africa.. A lot of those time zones never observe or no longer observe DST. The main countries that do are in Europe or North America, and most of their DST period are from March to Oct or April to Nov. Then we have a few exceptions in Australia, even then, there aren't that many to deal with. Most of the time, we won't cover them all unless your BI Platform is so big that it truly need to cover users from Marshall islands, Baghdad or New Guinea, which I highly doubt. I would say, this approach takes care of most cases and should be a good solution..

Thanks, until next time 


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