問題描述

我在這里做錯了什么?我只是從表中檢索結(jié)果，然后將它們添加到數(shù)組中.一切都按預(yù)期工作，直到我檢查結(jié)果為空...

What am I doing wrong here? I'm simply retrieving results from a table and then adding them to an array. Everything works as expected until I check for an empty result...

這會得到匹配項，將其添加到我的數(shù)組中并按預(yù)期回顯結(jié)果:

This gets the match, adds it to my array and echoes the result as expected:

$today = date('Y-m-d', strtotime('now'));

$sth = $db->prepare("SELECT id_email FROM db WHERE hardcopy = '1' AND hardcopy_date <= :today AND hardcopy_sent = '0' ORDER BY id_email ASC");

$sth->bindParam(':today', $today, PDO::PARAM_STR);

if(!$sth->execute()) {
    $db = null;
    exit();
}

while ($row = $sth->fetch(PDO::FETCH_ASSOC)) {
    $this->id_email[] = $row['id_email'];
    echo $row['id_email'];
}

$db = null;
return true;

當(dāng)我嘗試檢查空結(jié)果時，我的代碼返回空"，但不再產(chǎn)生匹配的結(jié)果:

When I try to check for an empty result, my code returns 'empty', but no longer yields the matching result:

$today = date('Y-m-d', strtotime('now'));

$sth = $db->prepare("SELECT id_email FROM db WHERE hardcopy = '1' AND hardcopy_date <= :today AND hardcopy_sent = '0' ORDER BY id_email ASC");

$sth->bindParam(':today',$today, PDO::PARAM_STR);

if(!$sth->execute()) {
    $db = null;
    exit();
}

if ($sth->fetchColumn()) {
    echo 'not empty';
    while ($row = $sth->fetch(PDO::FETCH_ASSOC)) {
        $this->id_email[] = $row['id_email'];
        echo $row['id_email'];
    }
    $db = null;
    return true;
}
echo 'empty';
$db = null;
return false;

推薦答案

當(dāng)您執(zhí)行 $sth->fetchColumn() 時，您將丟棄結(jié)果行.這不是您檢查是否有任何結(jié)果的方式.你做

You're throwing away a result row when you do $sth->fetchColumn(). That's not how you check if there are any results. You do

if ($sth->rowCount() > 0) {
  ... got results ...
} else {
   echo 'nothing';
}

相關(guān)文檔在這里:PDOStatement::rowCount

Relevant documentation is here: PDOStatement::rowCount

這篇關(guān)于檢查空結(jié)果(PHP、PDO 和 MySQL)的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！