The Activity Report
Relationship managers at Northline Bank get a monthly sheet showing how busy each of their customers has been, because a quiet account is usually an account on its way out. The ledger records a customer number rather than a name, and the managers do not know the numbers.
transactions — one row per movement of money. customer_id points at a row in customers; type is one of deposit, withdrawal or transfer; txn_date is the day it settled. The ledger is signed: money arriving in an account is stored as a positive amount, and money leaving it as a negative one, so a 600-dollar withdrawal is recorded as -600.
| id | customer_id | amount | type | txn_date |
|---|---|---|---|---|
| 1 | 1 | 500 | deposit | 2023-07-01 |
| 2 | 1 | -120 | withdrawal | 2023-07-03 |
| 3 | 2 | 1000 | deposit | 2023-07-02 |
| 4 | 2 | -300 | withdrawal | 2023-07-05 |
| 5 | 3 | 250 | deposit | 2023-07-04 |
| 6 | 3 | -600 | withdrawal | 2023-07-06 |
| 7 | 4 | 800 | deposit | 2023-07-07 |
| 8 | 4 | -450 | withdrawal | 2023-07-08 |
| 9 | 5 | 2000 | deposit | 2023-07-09 |
| 10 | 5 | -1500 | withdrawal | 2023-07-10 |
| 11 | 1 | -200 | transfer | 2023-07-11 |
| 12 | 3 | 400 | deposit | 2023-07-12 |
customers — one row per account holder at Northline. account_type is either checking or savings; city is the branch city the account belongs to.
| id | name | account_type | city |
|---|---|---|---|
| 1 | Farah Idris | checking | Chicago |
| 2 | Grant Boyle | savings | Miami |
| 3 | Hana Suzuki | checking | Chicago |
| 4 | Ibrahim Njoku | savings | Miami |
| 5 | Jade Wu | checking | Seattle |
Both tables already exist in the database — there is nothing to create or load.
Task: Write a query that returns two columns, name and txns, one row per customer with at least one movement, txns being how many movements that customer made. Busiest first; two customers on the same number come back in alphabetical order of name.
Example output — shape only, on invented customers and tallies:
| name | txns |
|---|---|
| Nadia Ferreira | 9 |
| Tobias Renner | 9 |
| Marisol Vega | 7 |
| Oscar Delacroix | 6 |
| Rune Halvorsen | 4 |
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