Return the average, minimum, maximum, and total transaction amounts.
SELECT avg(transaction_amount) ,  min(transaction_amount) ,  max(transaction_amount) ,   sum(transaction_amount) FROM Financial_transactions
SELECT avg(transaction_amount) ,  min(transaction_amount) ,  max(transaction_amount) ,   sum(transaction_amount) FROM Financial_transactions
[{'avg(transaction_amount)': 1329.0559999999998, 'min(transaction_amount)': 368.46, 'max(transaction_amount)': 1979.66, 'sum(transaction_amount)': 19935.839999999997}]