sql oracle select group by

Question

I have two tables by names CASTR and CABL . My query is

SELECT to_number(substr(CASTR_OPER_DATE, 1, 5))
      ,MAX(CABL_REL_DAY)
      ,CASTR_KW_CAAC
      ,cabl_avail_bal
FROM CASTR 
INNER JOIN CABL 
    ON CASTR_KW_CAAC = CABL_KW_CAAC
WHERE CABL_REL_DAY <= to_number(substr(CASTR_OPER_DATE, 1, 5))   
GROUP BY CASTR_OPER_DATE, CASTR_KW_CAAC, cabl_avail_bal

when I run this query it gives me all cabl_avail_bal columns, but I want only cabl_avail_bal which their cabl_rel_day is max and CABL_REL_DAY<=to_number(substr(CASTR_OPER_DATE,1,5)) condition is true.

Here is my table structures

Answer 1

Kindly try the below

WITH CABL_REL_DAY_MAX
  as 
      (SELECT to_number(substr(CASTR_OPER_DATE, 1, 5)) oper_date
      ,MAX(CABL_REL_DAY) cabl_rel_max
      ,CASTR_KW_CAAC

      FROM CASTR 
      INNER JOIN CABL 
      ON CASTR_KW_CAAC = CABL_KW_CAAC
      WHERE CABL_REL_DAY <= to_number(substr(CASTR_OPER_DATE, 1, 5))   
      GROUP BY CASTR_OPER_DATE, CASTR_KW_CAAC)
   select oper_date,
          cabl_rel_max,
          CASTR_KW_CAAC,
          CABL.cabl_avail_bal
  FROM CABL 
  INNER JOIN CABL_REL_DAY_MAX
  ON  CASTR_KW_CAAC = CABL_KW_CAAC
  WHERE CABL.CABL_REL_DAY=cabl_rel_max;

Answer 2

I would suggest using analytic functions, something like this:

SELECT to_number(substr(CASTR_OPER_DATE, 1, 5)), CABL_REL_DAY, CASTR_KW_CAAC, cabl_avail_bal
FROM (SELECT CASTR_OPER_DATE, CABL_REL_DAY, CASTR_KW_CAAC, cabl_avail_bal,
             row_number() over (partition by CASTR_KW_CAAC order by cable_rel_day desc) as seqnum
      FROM CASTR INNER JOIN
           CABL 
           ON CASTR_KW_CAAC = CABL_KW_CAAC
      WHERE CABL_REL_DAY <= to_number(substr(CASTR_OPER_DATE, 1, 5))   
     ) c
WHERE seqnum = 1;