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Vertical Penetration

hardSQLJoinsGroupByAggregationNULLs

'Penetration' is Loopwire marketing's word for how many companies in a sector it has actually won, as opposed to how much they pay. The figure wanted is a headcount of paying companies per sector — a customer holding three contracts is still one company won, and must not be allowed to make its sector look three times better than it is. Only companies with something still running count; a sector Loopwire won and later lost is not penetrated.

subscriptions — one row per contract. account_id points at a row in accounts. plan is the tier the customer bought. mrr is what that contract bills every month, in dollars. start_date is the day it began. A contract that has stopped carries the day it stopped in end_date; one that is still running has nothing there, shown as below and stored as NULL.

id account_id plan mrr start_date end_date
1 1 starter 49 2022-11-03 2023-02-03
2 1 growth 149 2023-02-03
3 2 growth 149 2022-12-15 2023-06-15
4 3 starter 49 2023-01-31
5 4 growth 149 2023-02-06
6 5 enterprise 499 2023-02-22
7 6 starter 49 2023-03-01 2023-04-01
8 7 growth 149 2023-03-22
9 8 enterprise 499 2023-04-28
10 2 starter 49 2023-06-15

accounts — one row per customer company. industry is the sector that company works in; signup_date is the day it created its Loopwire account.

id company_name industry signup_date
1 Northwind Traders retail 2022-11-03
2 Vertex Analytics software 2022-12-15
3 Bluepeak Logistics logistics 2023-01-20
4 Fernwood Studio media 2023-02-05
5 Cobalt Health healthcare 2023-02-18
6 Ridgeline Capital finance 2023-03-01
7 Sable & Co retail 2023-03-22
8 Hearth Robotics manufacturing 2023-04-10

Both tables already exist in the database — there is nothing to create or load.

Task: Write a query that returns one row per industry, with columns industry and active_accounts — how many separate companies in that sector hold at least one still-running contract, each company counted once no matter how many running contracts it holds. Sectors with no such company do not appear. Largest headcount first; equal headcounts are listed alphabetically by industry name.

Example output

Shape only — these sectors and headcounts are invented:

industry active_accounts
energy 4
education 1
hospitality 1
insurance 1
nonprofit 1

(...1 more row not shown)

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