I have the following table "numbers" in my MariaDB database:
| id | number |
|---|---|
| 1 | 25 |
| 2 | 41 |
| 3 | 3 |
| 4 | 73 |
| 5 | 38 |
| 6 | 41 |
| 7 | 12 |
| 8 | 14 |
Now I would like to create a view that lets me see:
- column 1: All possible numbers (distinct)
- column 2: the amount of occurrences of that number
- column 3: the amount of IDs between the last ID and the ID from that number.
That would result in this view:
| number | occurrences | IDdifferences |
|---|---|---|
| 3 | 1 | 5 |
| 12 | 1 | 1 |
| 14 | 1 | 0 |
| 25 | 1 | 7 |
| 38 | 1 | 3 |
| 41 | 2 | 2 |
| 73 | 1 | 4 |
So I started with:
"SELECT DISTINCT number FROM numbers" and then a left join on the same table to count , but that makes the query verrrry slow (and it didn’t work the way I wanted). Do you have any idea how to resolve this? Thanks a lot in advance!
>Solution :
Yo can group by number and use COUNT() aggregate function to get the column occurrences and MAX() window function to get the column IDdifferences:
SELECT number,
COUNT(*) occurrences,
MAX(MAX(id)) OVER () - MAX(id) IDdifferences
FROM numbers
GROUP BY number
ORDER BY number;
See the demo.