使用 PDO 查询显示数据的最佳实践

Question

将现有查询从 mysql_* 调用更新为 PDO 调用。有很多从数据库中提取数据然后用于各种显示能力的实例。为简单起见，假设您要做的就是制作从查询返回的一列的垂直列表。相同的概念可以填充屏幕上的表格列、下拉列表，但我们只是说，所需要的只是使用 PHP 在屏幕上每行显示一个数据单元格。

使用 MySQL 你可以：

Include('./dbconnect.php);//assume it is set up with to include the correct DB
$query = 'SELECT C1 FROM T1';
$result = mysql_query($query);
mysql_close($dbconn);//assume $dbconn is correct from dbconnect.php
// what ever amount of code between here and there but the connection is closed
while($row = mysql_fetch_assoc($result)){
echo $row['C1']."<br>";//prints the results one data set per row
}
// what ever else you need to code after this

您可以使用 PDO 执行查询，将其保存为数组并像上面的示例一样整齐地关闭连接，还是您必须等到运行类似的东西；

// The PDO connect, statement
// what ever amount of code between here and there but with connection still open
while($row = $stmt->(PDO::FETCH_ASSOC)){
echo($row['C1']."<br>";
}
$dbconn = null;  // finally close the connection after who knows how long
// what ever else you need to code after this

问这个问题的另一种方法可能是询问如果您执行以下语句，是否所有 PDO 属性都获得值：

$result = $stmt->execute;// assume the connection and statement were properly set up

您能否将连接设置为空，关闭它，稍后在代码中使用类似的东西：

While($row = $result->(PDO::FETCH_ASSOC)){
// what ever
}

并期望它起作用？

谢谢

Answer 1

我们只需要说，使用 PHP 在屏幕上每行显示一个数据单元格即可。

$query = 'SELECT C1 FROM T1';
$stmt  = $pdo->query($query);
$data  = $stmt->fetchAll();
// here you can close the connection, though it's absolutely unnecessary.
foreach($data as $row){
    // what ever
}