PDO/PHP-检查行是否存在 [英] PDO/PHP - Check if row exist

问题描述

我希望有一个条件，以防该行根本不存在.

I want to have a condition incase the row doesn't exist at all.

$stmt = $conn->prepare('SELECT * FROM table WHERE ID=?');
$stmt->bindParam(1, $_GET['id'], PDO::PARAM_INT);
$stmt->execute();
$row = $stmt->fetch(PDO::FETCH_ASSOC);

尝试了if (count($row) == 0)和if($stmt->rowCount() < 0)，但是它们都不起作用.

Tried if (count($row) == 0) and if($stmt->rowCount() < 0) but none of them works.

推荐答案

您可以直接检查返回值.

You can just check the return value directly.

$stmt = $conn->prepare('SELECT * FROM table WHERE ID=?');
$stmt->bindParam(1, $_GET['id'], PDO::PARAM_INT);
$stmt->execute();
$row = $stmt->fetch(PDO::FETCH_ASSOC);

if( ! $row)
{
    die('nothing found');
}

/*
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC); // Same here
if( ! $rows)
{
    die('nothing found');
}
*/

如果您要询问是否在不提取的情况下检查 ，则只需让MySQL返回1(或使用COUNT()命令).

If you are asking about checking without fetching then simply have MySQL return a 1 (or use the COUNT() command).

$sql = 'SELECT 1 from table WHERE id = ? LIMIT 1';
//$sql = 'SELECT COUNT(*) from table WHERE param = ?'; // for checking >1 records
$stmt = $conn->prepare($sql);
$stmt->bindParam(1, $_GET['id'], PDO::PARAM_INT);
$stmt->execute();

if($stmt->fetchColumn()) die('found');

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