如何设计MySQL数据库以支持会计系统中的账户和交易处理？

CREATE TABLE account (
  id INT PRIMARY KEY,
  name VARCHAR(255),
  type VARCHAR(50),
  balance DECIMAL(10,2)
);

CREATE TABLE transaction (
  id INT PRIMARY KEY,
  date DATE,
  description VARCHAR(255)
);

CREATE TABLE transaction_item (
  id INT PRIMARY KEY,
  transaction_id INT,
  account_id INT,
  amount DECIMAL(10,2),
  FOREIGN KEY (transaction_id) REFERENCES transaction(id),
  FOREIGN KEY (account_id) REFERENCES account(id)
);

INSERT INTO account (id, name, type, balance)
VALUES (1, '现金账户', '资产', 10000.00);

SELECT balance
FROM account
WHERE id = 1;

INSERT INTO transaction (id, date, description)
VALUES (1, '2022-01-01', '购买商品');

INSERT INTO transaction_item (id, transaction_id, account_id, amount)
VALUES (1, 1, 1, -2000.00);

SELECT t.date, t.description, a.name, ti.amount
FROM transaction AS t
JOIN transaction_item AS ti ON t.id = ti.transaction_id
JOIN account AS a ON ti.account_id = a.id
WHERE t.id = 1;