业务背景：电商业务中，需要给电商app设计一个用户钱包，用户可以往钱包中充值，购买商品时用户可以使用钱包中的钱消费，商品申请退款成功后钱会退回钱包中，用户也可以申请提现把钱提到银行卡中 用程序实现如下api接口 1. 查询用户钱包余额 2. 用户消费100元的接口 3. 用户退款20元接口 4. 查询用户钱包金额变动明细的接口 请给出建表语句和对应的代码（只要能实现上面api接口要求即可，不相关的表和代码不用写）

建表语句如下：

CREATE TABLE user_wallet (
  id INT PRIMARY KEY AUTO_INCREMENT,
  user_id INT NOT NULL,
  balance DECIMAL(10, 2) NOT NULL DEFAULT 0.00,
  created_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

CREATE TABLE wallet_transaction (
  id INT PRIMARY KEY AUTO_INCREMENT,
  user_id INT NOT NULL,
  type ENUM('RECHARGE', 'CONSUME', 'REFUND', 'WITHDRAW') NOT NULL,
  amount DECIMAL(10, 2) NOT NULL,
  balance DECIMAL(10, 2) NOT NULL,
  remark VARCHAR(255) DEFAULT NULL,
  created_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
);

对应的代码如下：

// 查询用户钱包余额
public BigDecimal getUserWalletBalance(int userId) {
    String sql = "SELECT balance FROM user_wallet WHERE user_id = ?";
    try (Connection conn = dataSource.getConnection();
         PreparedStatement ps = conn.prepareStatement(sql)) {
        ps.setInt(1, userId);
        try (ResultSet rs = ps.executeQuery()) {
            if (rs.next()) {
                return rs.getBigDecimal("balance");
            }
        }
    } catch (SQLException e) {
        // 异常处理
    }
    return BigDecimal.ZERO;
}

// 用户消费100元的接口
public void consumeFromUserWallet(int userId, BigDecimal amount) {
    String sql = "UPDATE user_wallet SET balance = balance - ? WHERE user_id = ?";
    try (Connection conn = dataSource.getConnection();
         PreparedStatement ps = conn.prepareStatement(sql)) {
        ps.setBigDecimal(1, amount);
        ps.setInt(2, userId);
        ps.executeUpdate();
        // 记录交易明细
        recordTransaction(userId, WalletTransactionType.CONSUME, amount.negate(), "用户消费");
    } catch (SQLException e) {
        // 异常处理
    }
}

// 用户退款20元接口
public void refundToUserWallet(int userId, BigDecimal amount) {
    String sql = "UPDATE user_wallet SET balance = balance + ? WHERE user_id = ?";
    try (Connection conn = dataSource.getConnection();
         PreparedStatement ps = conn.prepareStatement(sql)) {
        ps.setBigDecimal(1, amount);
        ps.setInt(2, userId);
        ps.executeUpdate();
        // 记录交易明细
        recordTransaction(userId, WalletTransactionType.REFUND, amount, "用户退款");
    } catch (SQLException e) {
        // 异常处理
    }
}

// 查询用户钱包金额变动明细的接口
public List<WalletTransaction> getUserWalletTransactions(int userId) {
    List<WalletTransaction> transactions = new ArrayList<>();
    String sql = "SELECT type, amount, balance, remark, created_time FROM wallet_transaction WHERE user_id = ? ORDER BY created_time DESC";
    try (Connection conn = dataSource.getConnection();
         PreparedStatement ps = conn.prepareStatement(sql)) {
        ps.setInt(1, userId);
        try (ResultSet rs = ps.executeQuery()) {
            while (rs.next()) {
                WalletTransaction transaction = new WalletTransaction();
                transaction.setType(WalletTransactionType.valueOf(rs.getString("type")));
                transaction.setAmount(rs.getBigDecimal("amount"));
                transaction.setBalance(rs.getBigDecimal("balance"));
                transaction.setRemark(rs.getString("remark"));
                transaction.setCreatedTime(rs.getTimestamp("created_time").toLocalDateTime());
                transactions.add(transaction);
            }
        }
    } catch (SQLException e) {
        // 异常处理
    }
    return transactions;
}

// 记录交易明细
private void recordTransaction(int userId, WalletTransactionType type, BigDecimal amount, String remark) {
    BigDecimal balance = getUserWalletBalance(userId);
    String sql = "INSERT INTO wallet_transaction (user_id, type, amount, balance, remark) VALUES (?, ?, ?, ?, ?)";
    try (Connection conn = dataSource.getConnection();
         PreparedStatement ps = conn.prepareStatement(sql)) {
        ps.setInt(1, userId);
        ps.setString(2, type.name());
        ps.setBigDecimal(3, amount);
        ps.setBigDecimal(4, balance);
        ps.setString(5, remark);
        ps.executeUpdate();
    } catch (SQLException e) {
        // 异常处理
    }
}