SQL - 检查上个月是否有项目可用，然后标记它

Question

I'm trying to solve a problem in SQL but without much success so far. I have a table like this:

OWNER|STORE|DATE
  A  | MIX |01/01/2019
  A  | BIX |01/01/2019
  A  | BIX |02/01/2019
  B  | CIX |01/01/2019
  B  | CIX |02/01/2019

It's a table showing information about owners and their stores. An owner can have a store during a month, but this store could be gone in the next month. Or, their store could be present in january, but gone in february.

I wanted to find a way to flag this store movement, so if a store is present in january, and gone in february, I would flag a colum as "gone". And if a store was not present in january, but appeared in february, I would flag it as "new".

Can anyone help me with that? Thanks!

Answer 1

Use lag() and lead() :

select t.*,
       (case when prev_date < add_months(date, -1) or
                  prev_date is null
             then 'new'
             when next_date > add_months(date, 1) or
                  next_date is null
             then 'gone'
        end) as flag
from (select t.*,
             lag(date) over (partition by owner, store order by date) as prev_date,
             lead(date) over (partition by owner, store order by date) as lead_date
      from t
     ) t;

Answer 2

SELECT 
    ID, 
    OWNER, 
    STORE, 
    DATE, 
    CASE WHEN DATE IN (SELECT DATE FROM TableName
WHERE DATE IN (<InsertDatesHere)) THEN 'NEW' ELSE 'Gone' END AS Flag

Answer 3

select d.store ,d.owner , d.timedate , 'new' flag from (
  SELECT
 a.store, count(a.store) as flag
FROM
  store as a
  left join  store as b
  on a.store=b.store
group by a.store
having(count(a.store)<2)) as c

  inner join store as d
  on c.store=d.store

union all
(SELECT
 a.store , a.owner, max(a.timedate ), 'gone' as [flag]
FROM
  store as a
  inner  join
  (SELECT
 owner,store,timedate

FROM store) as b
on b.store = a.store and a.timedate!=b.timedate
group by a.store , a.owner)

sqlfiddle here