Question

DATA given:

 inventory_num_id        inventory_group_id             num   code
         9681066                 100003894             211      E
         9679839                 100003894             212      E
         9687165                 100003894             213      E
         9680883                 100003894             214      I
         9710863                 100003894             515      E
         9681246                 100003894             516      E
         9682695                 100003894             517      E
         9681239                 100003894             518      E
         9685409                 100003894             519      E
         9679843                 100003894             520      C
         9679844                 100003894             521      C
         9714882                 100003894             522      E
         9679845                 100003894             523      I
         9681211                 100003894             524      E
         9681216                 100003894             525      E
         9682696                 100003894             526      E
         9681227                 100003894             527      E

Result examples should be like:

inventory_group_id   code start  end 
------------------   ---- -----  ---- 
         100003894      E   211   213
         100003894      I   214
         100003894      E   515   519
         100003894      C   520   521
         100003894      E   522
         100003894      I   523
         100003894      E   524   527

What operator should I use to make start as minimum and end as max value? And could you please explain what I should do when the end(maximum)is not supposed to present?

Can I use GROUP BY clause there somehow?

Answer 1

Ann, be careful on the dark side of sql.
There are more than one way to do it.
Here is the answer:

SELECT a.inventory_group_id,
   a.code,
  a.num        AS "start",
  decode(b.num,a.num,null,b.num) AS "end" FROM
  ( SELECT inventory_num_id,inventory_group_id,code,num
         , ROW_NUMBER() OVER (PARTITION BY inventory_group_id,code ORDER BY num) AS rn
    FROM inventory_num  a
    WHERE NOT EXISTS
          ( SELECT * 
            FROM inventory_num  prev
            WHERE prev.inventory_group_id = a.inventory_group_id
            and  PREV.CODE = a.code
              AND prev.num = a.num - 1
          ) 
  )  a
JOIN
  ( SELECT  inventory_num_id,inventory_group_id,code, num 
         , ROW_NUMBER() OVER (PARTITION BY inventory_group_id,code ORDER BY num) AS rn
    FROM inventory_num  a
    WHERE NOT EXISTS
          ( SELECT * 
            FROM inventory_num  next
            WHERE next.inventory_group_id = a.inventory_group_id
            and  next.CODE = a.code
              AND next.num = a.num + 1
          )
  )  b
ON  b.inventory_group_id = a.inventory_group_id and b.code = a.code
AND b.rn  = a.rn
order by 3;