What are total transaction amounts for each transaction type?
SELECT transaction_type ,  sum(transaction_amount) FROM Financial_transactions GROUP BY transaction_type
SELECT transaction_type ,  sum(transaction_amount) FROM Financial_transactions GROUP BY transaction_type
[{'transaction_type': 'Payment', 'sum(transaction_amount)': 8743.15}, {'transaction_type': 'Refund', 'sum(transaction_amount)': 11192.689999999999}]