account_id and day columns from the Transactions table.CASE statement to determine the signed amount of each transaction (positive for 'Deposit', negative for 'Withdraw').SUM window function to calculate the running total of the signed amounts, partitioned by account_id and ordered by day.balance.account_id and day.
erDiagram
Transactions {
int account_id
date day
ENUM type
int amount
account_id_day PK
}