Java优学网ResultSet教程：从基础查询到性能优化，轻松掌握数据库操作

// 这段代码让我第一次感受到数据的流动 Connection conn = DriverManager.getConnection(url, user, password); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("SELECT * FROM students");

// 这个简单的循环教会了我数据的节奏感 while(rs.next()) {

String name = rs.getString("student_name");
System.out.println("当前学生：" + name);

}

// 合理的fetchSize设置改变了数据获取的节奏 Statement stmt = conn.createStatement(); stmt.setFetchSize(100); ResultSet rs = stmt.executeQuery("SELECT * FROM large_table");

public User findUserById(int userId) {

String sql = "SELECT user_id, username, email, create_time FROM users WHERE user_id = ?";
try (PreparedStatement pstmt = connection.prepareStatement(sql)) {
    pstmt.setInt(1, userId);
    ResultSet rs = pstmt.executeQuery();
    
    if (rs.next()) {
        User user = new User();
        user.setId(rs.getInt("user_id"));
        user.setUsername(rs.getString("username"));
        user.setEmail(rs.getString("email"));
        user.setCreateTime(rs.getTimestamp("create_time"));
        return user;
    }
} catch (SQLException e) {
    logger.error("查询用户失败", e);
}
return null;

}

// 老方法 - 繁琐且容易出错 PreparedStatement pstmt = null; ResultSet rs = null; try {

pstmt = connection.prepareStatement(sql);
rs = pstmt.executeQuery();
// 处理结果集

} finally {

if (rs != null) try { rs.close(); } catch (SQLException e) { /* 记录日志 */ }
if (pstmt != null) try { pstmt.close(); } catch (SQLException e) { /* 记录日志 */ }

}

// 新方法 - 简洁安全 try (PreparedStatement pstmt = connection.prepareStatement(sql);

 ResultSet rs = pstmt.executeQuery()) {
// 处理结果集

}