Using OVER() if customer has watch gladiator then 1 else 0 SQL SERVER

Question

I think I need some guidance as to what is wrong in my query. I am trying to do

Watched_Gladiator=CASE WHEN FilmName IN (CASE WHEN FilmName LIKE \'%Gladiator%\'         


        

Answer 1

The following does what you want for all films:

select r.*,
       (case when row_number() over (partition by filmname order by date) = 1
             then 1 else 0
        end) as IsWatchedFirstAndGladiator
from results r;

For just Gladiator:

select r.*,
       (case when filmname = 'Gladiator' and row_number() over (partition by filmname order by date) = 1
             then 1 else 0
        end) as IsWatchedFirst
from results r;

Answer 2

So you're saying that:

SELECT Cust_Nr, Date, FilmName, 
       CASE WHEN FilmName LIKE '%Gladiator%' THEN 1 ELSE 0 END as WatchedGladiator
FROM YourTable
WHERE YourColumn = @somevalue

Doesn't work? Because according to the data you've given, it should.

EDIT:

Well based on Tim's comment, I would simply add this bit to the query.

   SELECT Cust_Nr, Date, FilmName, WatchedGladiator
   FROM
   (
      SELECT Cust_Nr, Date, FilmName, 
             CASE WHEN FilmName LIKE '%Gladiator%' THEN 1 ELSE 0 END as WatchedGladiator
      FROM YourTable
      WHERE YourColumn = @somevalue
   ) as wg
   WHERE WatchedGladiator = 1

Answer 3

So you want to group by customer and add a column if this customer watched a specific film?

You could do:

SELECT Cust_Nr, MAX(Watched_Gladiator) 
FROM( SELECT Cust_Nr, 
            Watched_Gladiator = CASE WHEN EXISTS
            (
              SELECT 1 FROM CustomerFilm c2
              WHERE c2.Cust_Nr = c1.Cust_Nr 
              AND   c2.FilmName LIKE '%Gladiator%'
            ) THEN 1 ELSE 0 END
     FROM CustomerFilm c1 ) X
GROUP BY Cust_Nr

Demo

But it would be easier if you used the customer-table instead of this table, then you don't need the group-by.

Answer 4

Try grouping up to the cust/film level:

select
cust_nbr,
case when film_name like '%Gladiator%' then 1 else 0 end
from
(
select
    cust_nbr,
    film_name
    from
    <your table>
    group by
    cust_nbr,
    film_name
) t

Or, as an alternative:

select distinct cust_nbr
from
<your table>
where 
filmname = 'Gladiator'