SQL - Group by the base of an ID

Question

My SQL is not really good, but I am improving.

I try to extract records from a table with sales data. I want to know how much profit was made by a retailer and its subsidiaries per month.

The retailer_id is build from the root of 5 digits and (if subsidiaries exist) an adjacent _ with two digits. Like so:

• without subsidiaries: 30000
• with subsidiaries: 30000_01, 30000_02

Code:

SELECT
    retailer_id,
    MONTH(Date(created_at)) AS month,
    SUM(grand_total) AS Totals
FROM 
    sales_table
GROUP BY 
    retailer_id, month

As you can imagine, the retailer with subsidiaries are still separated line items.

As requested, I will give an example:

raw data

retailer_id	month	grand total
10006	12	10
10006	9	20
10006	9	40
10006_10	12	40
10015	9	10
10015	11	10
10015	12	5
10015	11	20

expected result:

retailer_id	month	Totals
10006	12	50
10006	9	60
10015	9	10
10015	11	30
10015	12	5
10015	11	20

Thank you for your help!

Answer 1

The answer is 'left'. As in this one:

select 
 left(retailer_id, 5),
 Month(Date(created_at)) AS month,
 sum(grand_total) AS Umsatz
FROM sales_order
WHERE store_id = '2' AND NOT status = 'canceled' AND created_at between '2021-09-01' AND '2022-01-27'
GROUP BY left(retailer_id, 5), month
ORDER BY left(retailer_id,5);