CREATE TABLE Orders (order_id NUMBER, customer_id NUMBER, date_order_placed DATETIME, order_details VARCHAR2)
CREATE TABLE Financial_Transactions (transaction_id NUMBER, account_id NUMBER, invoice_number NUMBER, transaction_type VARCHAR2, transaction_date DATETIME, transaction_amount NUMBER, transaction_comment VARCHAR2, other_transaction_details VARCHAR2)
CREATE TABLE Invoices (invoice_number NUMBER, order_id NUMBER, invoice_date DATETIME)
CREATE TABLE Product_Categories (production_type_code VARCHAR2, product_type_description VARCHAR2, vat_rating NUMBER)
CREATE TABLE Accounts (account_id NUMBER, customer_id NUMBER, date_account_opened DATETIME, account_name VARCHAR2, other_account_details VARCHAR2)
CREATE TABLE Products (product_id NUMBER, parent_product_id NUMBER, production_type_code VARCHAR2, unit_price NUMBER, product_name VARCHAR2, product_color VARCHAR2, product_size VARCHAR2)
CREATE TABLE Invoice_Line_Items (order_item_id NUMBER, invoice_number NUMBER, product_id NUMBER, product_title VARCHAR2, product_quantity VARCHAR2, product_price NUMBER, derived_product_cost NUMBER, derived_vat_payable NUMBER, derived_total_cost NUMBER)
CREATE TABLE Customers (customer_id NUMBER, customer_first_name VARCHAR2, customer_middle_initial VARCHAR2, customer_last_name VARCHAR2, gender VARCHAR2, email_address VARCHAR2, login_name VARCHAR2, login_password VARCHAR2, phone_number VARCHAR2, town_city VARCHAR2, state_county_province VARCHAR2, country VARCHAR2)
CREATE TABLE Order_Items (order_item_id NUMBER, order_id NUMBER, product_id NUMBER, product_quantity VARCHAR2, other_order_item_details VARCHAR2)

Show sum transaction amount from each transaction type, could you order total number of transaction amount in desc order?
SELECT transaction_type, SUM(transaction_amount) FROM Financial_Transactions GROUP BY transaction_type ORDER BY SUM(transaction_amount) DESC
SELECT "transaction_type", SUM("transaction_amount") FROM "Financial_Transactions" GROUP BY "transaction_type" ORDER BY SUM("transaction_amount") DESC