Query out of historic data table?

Question

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The scenario: A table of historical data showing state registration information. An example of the data looks like this:

ID	State	Status	AsOfDate
2021	AZ	A	2001-05-21
2021	AZ	T	2004-12-31
2021	AZ	A	2010-01-01
2021	CA	A	2001-05-21
2021	WA	A	2001-05-21
2023	AZ	A	2005-01-04
2023	MD	A	2003-07-01
2023	WA	A	2002-05-21
2023	WA	T	2007-05-21

ID = field rep identification number
State = state where a rep is licensed to work
Status = flag indicating Active or Terminated
AsOfDate = the date when the status changed

I need to figure out the query that will return the set of distinct states that are currently active for a given ID. That is to say, 2021 should return {AZ, CA, WA} (AZ was terminated and later reactivated) and 2023 should return {AZ, MD} (WA is still terminated.)

I would think this is a simple one, but I can't quite figure it out.

Posted 9-Feb-11 6:31am

Gregory Gadow

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Umair Feroze · Accepted Answer · 2011-02-09T06:58:00

Solution 2

The following query will work for you:

SQL

SELECT T.* FROM TestT T
JOIN (SELECT ID, State, MAX(AsOfDate) AsOfDate FROM TestT
GROUP BY ID, State) A ON T.Id = A.Id AND T.AsOfDate = A.AsOfDate
WHERE T.id = 2023
AND Status = 'A'

In this script TestT is the actual table which contain your data. Change the T.Id as per your need.

Hope this will help you.

Posted 9-Feb-11 6:58am

Umair Feroze

Comments

Gregory Gadow 9-Feb-11 13:29pm

Yup, that works! Thanks.