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Who Funds Their Account?

mediumSQLJoinsFilteringGroupBy

Deposit behaviour is what separates a saver from someone using Northline Bank as a pass-through, so the retention team wants each customer's funding total for the month. Only money coming in counts; what they did with it afterwards is a different report.

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 deposited, one row per customer who made at least one deposit, deposited being the total of their deposit amounts rounded to 2 decimal places. Largest total first; two customers on the same total come back in alphabetical order of name.

Example output — shape only, on invented customers and totals:

name deposited
Marisol Vega 9400
Oscar Delacroix 7100
Nadia Ferreira 5250
Tobias Renner 3300
Rune Halvorsen 1900

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