How can I sum a group of a custom calculated field in SQL?

Question

I have many shopper records who have a unique ID, there will be instances where a shopper with the same ID exists and I would like to sum up their shoppable_rated score and only return 1 result of the total sum of shoppable_rated for those IDs, so there will be no duplicate rows for the ID and their total score will be added up. Please can you advise how I would change my query? I got a little stuck trying to use HAVING and couldn't figure it out.

Many thanks!

SELECT 
    id, 
    shoppable,
    day,
    case when shoppable in ('Good','Very Good','Amazing') then 1 else 0 end as shoppable_rated
FROM 
    shoppers
WHERE
    shoppable != 'Unknown'
GROUP BY 
    id
ORDER BY 
    shoppable_rated DESC;

Example of my data:

id, shoppable, day, shoppable_rated
1, Good, 26, 1
2, Very Good, 14, 1
3, Not Great, 3, 0
1, Bad, 16, 0
3, Amazing, 30, 1

Answer 1

First, remove all the unaggregated columns that are not needed in the result set.

Second, use an aggregation function:

SELECT id,
       SUM(case when shoppable in ('Good','Very Good','Amazing') then 1 else 0 end) as shoppable_rated
FROM shoppers
WHERE shoppable <> 'Unknown'
GROUP BY id
ORDER BY shoppable_rated DESC;

If you need the data by id and day, then include both columns in both the SELECT and the GROUP BY :

SELECT id, day,
       SUM(case when shoppable in ('Good','Very Good','Amazing') then 1 else 0 end) as shoppable_rated
FROM shoppers
WHERE shoppable <> 'Unknown'
GROUP BY id, day
ORDER BY shoppable_rated DESC;