Question

Assuming data such as the following:

  ID      EffDate            Rate
   1      12/12/2011         100
   1      01/01/2012         110
   1      02/01/2012         120
   2      01/01/2012          40
   2      02/01/2012          50
   3      01/01/2012          25
   3      03/01/2012          30
   3      05/01/2012          35

How would I find the rate for ID 2 as of 1/15/2012?
Or, the rate for ID 1 for 1/15/2012?

In other words, how do I do a query that finds the correct rate when the date falls between the EffDate for two records? (Rate should be for the date prior to the selected date).

Thanks,
John

Answer 1

How about this:

SELECT Rate 
  FROM Table1 
 WHERE ID = 1 AND EffDate = (
  SELECT MAX(EffDate) 
    FROM Table1 
   WHERE ID = 1 AND EffDate <= '2012-15-01');

Here’s an SQL Fiddle to play with. I assume here that ‘ID/EffDate’ pair is unique for all table (at least the opposite doesn’t make sense).