SQL joining question

Question

Here is my situation:

I have one table that contains a list of drugs sold containing the NDC (an identifier), quantity sold, and whether the drug is a brand name or

Answer 1

This would get you each one on a separate line:

SELECT
  `cl`.`ndc`,
  `cl`.`rx_num`
FROM `claims_list` AS `cl`
WHERE `cl`.`ndc` IN
  (
    SELECT `dl`.`ndc` FROM `drug_list` AS `dl`
    WHERE `dl`.`type` = 'Generic'
    ORDER BY `dl`.`qty` DESC
    LIMIT 50
  )
ORDER BY `cl`.`date` DESC
LIMIT 4

Then run the results through a filter in the calling script to group them together.

Answer 2

Making some assumptions, and I'm not sure the exact Oracle syntax....but what about:

SELECT
    "ndc" as NDC,
    ( SELECT "rx_num" from "rx" WHERE "ndc"="drug_list"."ndc" ORDER BY "date" DESC LIMIT 1 OFFSET 0 ) as RX1,
    ( SELECT "rx_num" from "rx" WHERE "ndc"="drug_list"."ndc" ORDER BY "date" DESC LIMIT 1 OFFSET 1 ) as RX2,
    ( SELECT "rx_num" from "rx" WHERE "ndc"="drug_list"."ndc" ORDER BY "date" DESC LIMIT 1 OFFSET 2 ) as RX3,
    ( SELECT "rx_num" from "rx" WHERE "ndc"="drug_list"."ndc" ORDER BY "date" DESC LIMIT 1 OFFSET 3 ) as RX4
FROM "drug_list"
ORDER BY qty ASC
LIMIT 4

NDC | RX1 | RX2 | RX3 | RX4
123   2332  2342  2346  7776

Answer 3

You can use a combination of Analytics (if you are on a recent enough version of Oracle) and a Pivot Table to do it. This should work with your dataset.

select ndc,
       max(decode(rn, 1, rx_num, null)) rx1,
       max(decode(rn, 2, rx_num, null)) rx2,
       max(decode(rn, 3, rx_num, null)) rx3,
       max(decode(rn, 4, rx_num, null)) rx4
  from (select *
          from (select claims_list.ndc,
                       claims_list.rx_num,
                       row_number() over (partition by claims_list.ndc order by claims_list.date desc) rn
                  from claims_list,
                       (select * 
                          from (select *
                                  from drug_list
                                 where type = 'Generic'
                                order by qty desc
                               )
                         where rownum < 51
                       ) drug_list
                 where drug_list.ndc = claims_list.ndc
               )
         where rn < 5
        order by ndc, rn
       )
group by ndc;

The inner query uses analytics to pull the most recent 4 rx numbers for each drug based on the claim date. Then we use a pivot to take it from 4 lines per drug to one line with 4 columns.