如何使用 PDO 获取一行

2021-12-26 00:00:00 php pdo

我尽量不感到沮丧，但我最近了解到 mysql_* 在 PHP 中已被弃用.我决定学习如何使用 PDO.

I'm trying not to get frustrated, but I've recently learned that mysql_* is deprecated in PHP. I've decided that I would learn how to use PDO.

今天下午我刚刚在看它，使用它连接到数据库很容易，但后来我想用它获取一行并将该行保存为由列名索引的数组(同样的方式正如函数 mysql_fetch_array 所做的那样).我想不出它来挽救我的生命.

I've just been looking at it this afternoon, and connecting to the database using it was easy, but then I wanted to fetch a row with it and save the row as an array indexed by the column names (the same way as the function mysql_fetch_array did). I can't figure it out to save my life.

我会发布我的代码来澄清，我确信它很简单(所有编程错误总是很简单)，但我肯定做错了什么.

I'll post my code to clarify, and I'm sure it is something simple (all programming errors are always simple), but I am definitely doing something wrong.

// Connect to the database
$host    = $_PARAM["DatabaseServer"];
$db        = $_PARAM["MainDatabase"];
$dbuser    = $_PARAM["DatabaseUser"];
$dbpass    = $_PARAM["DatabasePass"];
try
{
    $Database = new PDO("mysql:host=$host;dbname=$db", $dbuser, $dbpass);
}
catch (PDOException $e)
{
    echo "There was an unexpected error. Please try again, or contact us with concerns";
}

$stmt = $Database->prepare("SELECT * FROM users WHERE username=?");
$stmt->execute(array($sUserCook));
$row = $stmt->fetchAll(PDO::FETCH_ASSOC);

echo $row["username"];

推荐答案

fetchAll 做它所说的:它获取查询的所有结果.由于它获取了大量结果，因此您将获得一个索引数组.

fetchAll does what it says: it fetches all results for a query. Since it fetches a lot of results, you'll get an indexed array.

fetch 会执行您可能正在寻找的操作:它为查询获取一个结果.如果您要将 mysql_* 代码转换为 PDO，最快的方法是使用此方法而不是 mysql_fetch_assoc.

fetch does what you might be looking for if you want only one row: it fetches one result for a query. If you're converting mysql_* code to PDO, the quickest way would be to just use this method instead of mysql_fetch_assoc.

如果您仍然使用 fetchAll:您的代码可能看起来像这样:

If you're still going with fetchAll: your code would probably just look like this:

$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
foreach ($rows as $row) {
    echo $row['username'];
}

就像我说的，如果您只是将遗留代码转换为 PDO 代码，将所有查询更改为准备好的语句并替换以下内容可能会更容易:

Like I said, if you're just converting legacy code to PDO code, it might be easier to just change all queries to prepared statements and replace the following:

  • mysql_fetch_assoc($result)
    -> $stmt->fetch(PDO::FETCH_ASSOC)
  • mysql_num_rows($result)
    -> $stmt->rowCount()
  • while ($row = mysql_fetch_assoc($result)) {}
    -> foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $row) {}

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