java更新数据库操作

try {
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "user", "password");
    String sql = "UPDATE users SET name = ? WHERE id = ?";
    PreparedStatement pstmt = conn.prepareStatement(sql);
    pstmt.setString(1, "newName");
    pstmt.setInt(2, 1);
    int affectedRows = pstmt.executeUpdate();
    if (affectedRows == 0) {
        System.out.println("No rows updated.");
    }
} catch (SQLException e) {
    e.printStackTrace();
}

try {
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "user", "password");
    conn.setAutoCommit(false); // 关闭自动提交
    String sql = "UPDATE users SET balance = balance - 100 WHERE id = ?";
    PreparedStatement pstmt = conn.prepareStatement(sql);
    pstmt.setInt(1, 1);
    pstmt.executeUpdate();
    conn.commit(); // 提交事务
} catch (SQLException e) {
    conn.rollback(); // 回滚事务
    e.printStackTrace();
}